ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 163 



"work bearing chromatin-granula or cytoblasts (chiefly basichromatin). 

 Finer than this is the " linin-f ramework " which traverses the whole 

 body of the nucleus and unites the nucleolar apparatus and the micro- 

 somes (chiefly oxychroniatin). In the meshes of the chromatin and 

 linin-f ramework there are the cyanophil granules (Altmann's granula). 



Structure and Development of Cartilage.* — 0. V. Srdinko has 

 studied this in man and mammals, in adult and embryonic stages. In 

 the embryonic condition the hyaline cartilage has cells with numerous 

 long ramifying protoplasmic processes. These cells have no capsule, 

 .and divide so that rows of daughter-cells arise. Many are in very 

 young stages united by plasmic anastomoses. The fundamental sub- 

 stance is homogeneous or fibrillated ; the fibrillation follows in conse- 

 quence of the impenetration of nutritive juices. This embryonic 

 cartilage leads directly to hyaline cartilage, the cells losing the strong 

 processes and becoming surrounded by a capsule. Part of the funda- 

 mental substance undoubtedly arises by direct modification of the 

 cells. 



In mature hyaline cartilage, there is no persistence of the embryonic 

 processes. Bundles of fine fibres are seen in the fundamental substance 

 running from cell to cell. The nutrition of the cartilage is probably 

 ■effected by impenetration of fluids along the fine bundles of fibres, 

 "which in this way come to stand out clearly amid the matrical 

 substance. 



Development and Structure of Vitreous Humour.f — P. Bertac- 

 chini has studied this in various mammals. He comes to the following 

 conclusions among others. The vitreous humour is not a connective 

 tissue in which the cells have disappeared by atrophy, nor a simple 

 vascular transudation, nor a secretion of retinal cells ; and it has no 

 developmental connection with the small quantity of mesoblast which 

 remains included in the optic cup or enters by the choroid fissure. It 

 is a tissue of secondary origin, exclusively clue to the blood-vessels 

 through the 'mediation of leucocytes. The original vitreous cells are 

 leucocytes which have passed from the blood by diapedesis. The 

 humour never loses its cells, though these are superficially disposed. 



The intercellular substance of the vitreous humour is secreted by 

 the vitreous cells in all the stages of development. In early fcetal life, 

 the cells secrete an unstainable gelatinous substance, which appears as 

 gelatinous spheres in the cytoplasm, and passes out by dehiscence. 

 Subsequently the mode of secretion changes a little ; it is associated 

 ■with the formation of stainable granules and the detachment by clasma- 

 tosis of plasmic prolongations. After birth this is the only method. 

 It is probable that the gelatinous drops give rise to the aqueous part of 

 the corpus vitreum, and that the detached plasmic fragments with their 

 stainable granulations form the denser part, and the mucin in particular. 



Structure of Digestive Canal in Reptiles. J — F. Beguin gives an 

 account of the minute structure of the digestive canal in common 



■■&" 



* Anat. Anzeig., xxii. (1903) pp. 437-46. 



t Internat. Monatschr. Anat. Physiol., xix. (1902) pp. 77-118 (2 pis.). 



% Rev. Suisse Zool., x. (1902) pp. 251-397 (6 pis.). 



M 2 



