ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 395 



elements which had grown in ; and further, in cells within the meshes no 

 development of connective substance was to be observed, even after a 

 long time. 



The research concludes with a chapter on the epithelioid and giant 

 cells, and with further discussion of the relation of wandering cells 

 to the problems of histogenesis. 



Histology of Nerve-fibres.* — Herr Joseph has investigated the 

 accuracy of Kupffer's conclusion that the axis cylinder of medullary 

 nerve-fibres was fibrillar in structure. As the object of investigation he 

 chose the electric nerves of Torpedo marmorata. 



His results led him to conclude (a) that in the axial space there is a 

 fine network, in the meshes of which the nerve-fibrils lie. In a normal 

 nerve-fibre the axial space must include the greatest contingent of fibres, 

 and exceed by five or more times the diameter of the medullary sheath. 

 In this axial space a network is for the first time distinctly determined. 

 The author criticizes as without sufficient basis the recent conclusions of 

 Nausen. (b) In the medullary sheath, he notes, besides the fat-spherules 

 (stained grey with osmic acid), a strongly refractive, generally darkly 

 stained framework. He believes that there is a second constituent 

 in the medullary sheath. This Ewald and Kuhne proposed to term 

 " neurokeratin," but as Herr Joseph failed completely to verify their 

 experiments (in which this framework persisted in digestion), he thinks 

 that the use of the term is unjustifiable. 



Development of Red Blood-corpuscles-t — M. L. Cuenot submits the 

 results of his observations on the development of the coloured corpuscles 

 of the blood, (a) The spleen of any of the lower vertebrates includes 

 two sets of nuclei, surrounded by a little protoplasm. The smaller are 

 the nuclei of the red blood-corpuscles ; the larger become amoeboid white 

 blood-corpuscles, (b) The rest of the development must be studied in 

 the blood. He is convinced that the nucleus of the leucocyte never 

 developes into a red blood-corpuscle, (c) The smaller nuclei above 

 mentioned acquire a more regularly contoured surrounding of proto- 

 plasm. The nucleus gives off from its surface little refractive granules, 

 and becomes in consequence reduced in size. At adult size the secretion 

 of hemoglobin begins in the cell. The nucleus thus appears to have an 

 important role in the formation of haemoglobin. The process was 

 observed in fishes, amphibia, reptiles, and birds, (d) In mammals the 

 development above indicated takes place wholly within the spleen. 



B. INVERTEBRATA. 



Ccelom and Vascular System of Mollusca and Arthropoda.J — Prof. 

 E. Ray Lankester points out that the system of blood-containing spores 

 which pervades the body of Molluscs and Arthropods is not equivalent 

 to the ccelom or perivisceral space of Chaatopoda and Vertebrata, but is 

 a distended and irregularly swollen vascular system ; the cavities may 

 be called " haemoccel " in contradistinction to ccelom. In the Mollusca 

 the chief representative of the true ccelom is the pericardial space ; this 

 does not communicate with the vascular system and does not contain 



* Arch. f. Anat. u. Physiol. (Anat. Abtheil.), 1888, pp. 184-7 (Physiol. Gesell. 

 Berlin). 



t Comptes Eendus, cvi. (1888) pp. 673-5. t Nature, xxxvii. (1888) p. 498. 



