External Filaments Research Articles

Intracellular Treponema pallidum in cells of a syphilitic lesion of the uterine cervix

In an electron microscopic study of biopsy tissue from an ulcer of the human cervix uteri, organisms morphologically identical to T. pallidum were observed. Large numbers of the organisms were seen lying among collagen fibrils and between cells. T. pallidum was seen within vacuoles of some fibroblasts and epithelial cells. Within the nucleoplasm of several cells, treponemes were observed, surrounded by a clear zone which might represent a mucopolysaccharide outer layer. The diameter of the organisms was 171 nm., and the diameter of the external axial filaments was 25 nm., dimensions similar to those reported by others for T. pallidum.

The fine structure of the frontal filament complex of barnacle larvae (Crustacea: cirripedia).

The frontal filaments comprise two regions, the internal vesicles and the external filaments. Dendrites of extra-optic protocerebral origin pass ventrally from the brain, some terminating within the lumen of the vesicles, others passing to the external filaments. Those dendrites within a vesicle have greatly swollen terminations from which two pairs of cilia arise. These cilia have well developed basal bodies, striated rootlets and a basal 9 + 0 fibrillar arrangement; they are also branched, the projections of a cilium being closely aligned. Within the external filaments dendrites terminate at different levels. Basally a pair of branched cilia, similar in form to the cilia within the vesicle, arise from a single swollen dendritic termination. The ciliary projections, however, are short and their ends bulbous. Nine simple cilia arise from dendrites with non-swollen terminations. Some of these simple cilia may be joined together laterally by extensions of their shafts and abut apically on the hypodermal cell-membranes. Further apically in the filament a single branched cilium arises from a non-swollen dendritic termination. The function of frontal filaments is unknown, but it is thought to be sensory; the possible sensory functions which may be involved are discussed.

Laminariocolax Tomentosoideson the Isle of Man

SUMMARYLaminariocolax tomentosoidesis a common epi-endophyte on the I.O.M. Though probably pseudoperennial as an endophyte it produces fertile external filaments only from September to June with a March maximum in size and numbers. It reproduces vegetatively by growing through its host's tissues and asexually by means of zoospores from plurilocular sporangia. In culture, zoospores give rise to fertile plants in 7 days and several generations can be produced in 4 weeks. The offspring bear only plurilocular sporangia. The chromosome number is apparently 16 and the life-history probably a postponed series of diplonts.Laminariocolax tomentosoidesproduces cysts which, in the past, have been mistakenly identified as unilocular sporangia and which are so similar to the ascocysts of Ascocyclus that this genus would seem to be based on a character of little value. Another description of unilocular sporangia in the species is tentatively attributed to infection by a fungus.

A COMPARATIVE ACCOUNT OF THE PROTONEPHRIDIA OF ASPLANGHNA (ROTIFERA) WITH SPECIAL REFERENCE TO THE FLAME BULBS

The protonephridia of the females of three species of Asplanchna are described and compared. Each protonephridium consists of a single unbranched coiled tubule, divisible into a distal capillary tubule receiving ducts from the flame bulbs and a wider proximal main tubule entering the contractile vesicle. Each flame bulb is of flattened triangular form with longitudinally‐striated thin lateral walls and a thick terminal wall bearing internally the vibratile flame and externally a number of external filaments anchoring the flame bulb to the body wall.The numbers of flame bulbs in the species of Asplanchna are compared. Information available suggests that there is a close correlation between the number of flame bulbs and the surface area of the animal. The surface area per bulb is less in males than in females of the same species and there is some evidence that the number of bulbs in males is less than that of the larger females.Females of species of differing body size have flame bulbs of similar length and the estimated output of fluid per flame bulb is similar in each. It is suggested that an increase in number rather than size of bulbs accounts for the increased output from the contractile vesicle of the larger species, and that there is an optimum size for the flame bulb. The output per bulb in males is less than that of females of the same species and it is suggested that the absence of a gut in males may account for this difference.

Observations on the Torpedo, with an account of some additional experiments on its electricity

The first part of this paper is occupied by an investigation of the circumstances attending the fœtal development of the Torpedo. In the first stage of embryonic growth which the author had an oppor­tunity of observing, when the embryo was about seven tenths of an inch in length, it had neither fins nor electrical organs, nor any ap­pearance of eyes; it exhibited short external branchial filaments, not yet carrying red blood; and there was a red spot in the situation of the heart, communicating by red vessels in the umbilical cord with the vascular part of the egg. There is no membrane investing the fœtus, as is the case with some species of Squall ; nor any fluid in the uterine cavity; neither could the author find any urea or Iithic acid in that cavity. By taking the mean of many observations, it appeared that the weight of the egg, before any appearance of the embryo, is 182 grs., and after its appearance, including the weight of the latter, 177 grs.; while the weight of the mature fish is about 479 grs.; showing an augmentation of more than double. Thus it differs remarkably, in this respect, from the fœtal chick, which at its full time weighs consider­ably less than the original yolk and white from which it is formed. No communication can be traced between the fœtus of the Torpedo and the parent, through the medium of any vascular or celiular structure; and the stomach of the former is always found empty. Hence the only apparent source of nourishment is absorption from the surface; and the author states his reasons for believing that the branchial fila­ments are the principal absorbing organs, the materials they receive being chiefly employed in the construction of the electrical organs, while those which enter into the composition of the body generally are absorbed by the general surface of the fœtus. The author is led, from his researches, to the conclusion that the mode of reproduction in the Torpedo is intermediate between the viviparous and the ovoviviparous. In the second part of the paper, the author discusses the question as to the number of species of the genus Torpedo existing in the Mediterranean; and concludes that there are only two, viz. the Ochiatella and the Tremola .