196 SUMMARY OF CURRENT RESEARCHES RELATING TO 



produced by tho trans-section of the tubes, and the meshes of the reticu- 

 lation are merely the trans-sected sheaths ; the interfibrillar substance 

 of authors is the hyalino hyaloplasm, which is the real nervous sub- 

 stance. The tubes and fibrils, of which the dotted substance is made 

 up, consist of (1) the branches of the nervous processes that lose their 

 individuality and are entirely broken up into slender branches ; (2) 

 the side branches of those nervous processes, which do not lose their 

 individuality but directly become nerve-tubes, while giving off side 

 branches on their course through the dotted substance ; (3) the longi- 

 tudinal nerve-cords which run through the dotted substance; (4) the 

 side branches given off from those nerve-tubes ; (5) the branches of 

 such longitudinal nerve-tubes as are entirely broken up into slender 

 branches and lose themselves in the dotted substance ; (6) the slender 

 tubes or fibrils which unite to form the peripheral nerve-tubes which 

 exclusively arise from the substance ; (7) the side branches joining 

 those peripheral nerve-tubes which spring directly from ganglion-cells. 

 In addition to tubes and fibrils, neuroglia cells and fibres are to be found 

 in dotted substance ; the nuclei generally have an oblong shape and a 

 granular appearance. 



The author next proceeds to discuss the combination of the ganglion- 

 cells with one another, and the function of the protoplasmic processes ; 

 in spite of all his trouble Mr. Nansen has been unable to find any direct 

 anastomosis between the processes of the ganglion-cells, and he does not 

 think that, as a rule, such exists. With Prof. Golgi, he believes that 

 the protoplasmic processes of the cells have a nutritive function, and 

 that when the cells cannot get sufficient nutrition in their neighbourhood, 

 they have to send out processes towards tho periphery of the nervous 

 system, or into the loose neuroglia reticulation, where there is sufficient 

 nutritive fluid for the processes to absorb. If there is any combination 

 between the ganglion-cells it must be due to the nervous processes. 

 There are, it is to be remembered, two types of ganglion processes : some 

 become directly nerve-tubes, and do not lose their individuality, while 

 others are subdivided into a number of slender branches which are lost 

 in the dotted substance; Mr. Nansen thinks it possible that these 

 communicate with one another. 



A brief preliminary notice is given of the nervous elements of 

 Amphioxus and Myxine : it seems that they agree essentially with those 

 of bilateral invertebrates. 



In conclusion, the combination of the nerve-tubes is discussed, and 

 the author suggests that in a reflex-curve the centripetal nerve-tube, the 

 central web or interlacing of nervous fibrils, and the centrifugal nerve- 

 tube are the sole elements ; in other words, he believes that the ganglion- 

 cells take no part in the matter ; these last he looks upon as having 

 nutritive functions, while the more the intelligence of an animal is 

 developed, the more intricate becomes the web of nerve-tubes and fibrils 

 in its dotted substance. 



Artificial Deformations of the Nucleus.* — Prof. C. Van Bambeke 

 finds that the nuclei of vegetable cells, of Arthropoda, and probably 

 nuclei in general, show under certain conditions artificial deformations 

 which throw light on the structure of these elements. These either 

 affect the nuclear filament or several constituent parts of the nucleus. 



* Arch, de Biol, vii. (1887) pp. 348-87 (3 pis.). 



