ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 133 



b. Histology. 



Endoplasm and Exoplasm.* — F. K. Studnicka has studied in the 

 note-chord of Belone aeas and in the dental papillae of the horse, cellular 

 processes which throw light on the formation of the endoplasm or 

 deutendoplasma on the one hand and on the nature of the ectoplasm 

 (individual ectoplasm as contrasted with synexoplasm) on the other. 



Plasmic Structures.! — Julius Arnold, one of the veteran cytologists, 

 has collected his chief observations and conclusions in a book. He 

 discusses plasmosomes and chondriosomes, mitosomes and mitochondria, 

 and shows that cellular pathology and physiology must be deepened by 

 a recognition of the importance of the granula. The independence of 

 the microsomes is limited, and though their role is sometimes quite 

 definite, there are pathological and normal processes which demand 

 a recognition of the co-ordinated life of the cell as a whole. 



Movements of Melanophores of Frog. J — S. J. Holmes publishes 

 the results of a further series of observations on the reactions and move- 

 ments of isolated melanophores of the frog. He finds that black pigment 

 cells in tissues from the frog cultivated in lymph or plasma sometimes 

 wander out free from other cells. The pigment cells show a typical 

 amoeboid movement, and may creep to a considerable distance. The 

 smaller melanophores are relatively more active, and become isolated 

 more often than the larger ones. Processes may be formed that are 

 mostly free from pigment, and pigment may flow back and forward within 

 cell processes. The changes observed in the pigmentation of the 

 chromatophores are partly due to variation in the distribution of 

 pigment within the cell, and partly due to changes in the outline of the 

 cell itself. Heat causes a withdrawal of cell processes. Light has very 

 little influence in the movements or state of contraction of the melano- 

 phores. Pigment-cells show a positive tkigrnotaxis, the newly formed 

 pseudopods being adhesive to solid bodies. 



Chondriosomes of Cartilage Cells. § — Luigi Torraca has studied 

 these in the newt's tail during the process of regeneration. Some of the 

 cells of the blastema along the axis of the regenerating bud are trans- 

 formed into chondrioblasts. During this transformation the chondrio- 

 konts increase in length and thickness and number. The staining 

 reactions change. 



In the mitosis of the cartilage cells the chondriome does not seem 

 to participate actively. During the karyokinesis the mitochondria seem 

 more numerous than chondriokonts, but these do not completely dis- 

 appear. When the nucleus passes into a resting stage the chondrio- 

 konts again predominate. 



When the ossification of the vertebras begins,- the cartilage cells 



* Anat. Anzeig., xlv. (1914) pp. 438-58 (27 figs.). 



t Ueber Plasmastrukturen und ihre funktionelle Bedeutung. Jena, 1914, 

 xviii and 471 pp. (4 pis.). See also Anat. Anzeig., xlvii. (1914) pp. 367-8. 

 X Univ. California Publications (Zool.) xii. (1914) pp. 167-74 (1 pi.). 

 § Anat. Anzeig., xlv. (1914) pp. 459-74 (5 figs.). 



