ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 299 



the mingling now described occurs throughout the general branchial 

 epithelium. In the lamprey there is a normal mingling of endoderm and 

 mesenchyme in forming the thymus, but the cells of the greater portion 

 of the mixed tissue are transformed into leucocytes, indicating the histo- 

 genetic relationship of lymphocyte formation (and probably erythrocyte 

 formation) to thymus formation in this primitive animal. J. A. T. 



Minute Structure of Sensory Root of Trig;eminal Nerve. — L. A. 

 HoAG {Anat. Record, 1918, 14, 165-82) has studied this in 3Ius nor- 

 vegicus. The peripheral supporting tissues, endoneurium and epineurium, 

 together with the neurolemma, meet, without intermingling, the central 

 supporting tissues, neuroglia and pia mater, to form an indefinite lamina 

 cribrosa, through which the bundles of nerve-fibres pass. There seem 

 to be distinct chemical and physical differences between the central and 

 peripheral myelin. A number of other mammals show a similar or 

 identical picture. J. A. T. 



c. Greneral. 



Seasonal Changes in Kidney of Stickleback. — Walter X. Hess 

 {Anat. Record, 1918, 14, 141-63, 10 figs.) has made a study of the 

 kidney of the five-spined Eucalia inconstans cayuga. For most of the 

 year it is an excretory organ. At the breeding season the uriniparous 

 tubules and glomeruli remain excretory, while the epithelial cells of the 

 muciparous tubules, urinary ducts, bladder, and common urinary duct 

 become modified for producing slime. The nuclei seem to pour into 

 the cell-bodies certain products, in the form of secretion granules, which 

 function in breaking down the granular cytoplasm. The secretion 

 granules seem to be produced from certain products of the karyoplasm. 

 The making of the adhesive slime which glues, rather than ties, the 

 material of the nest together is probably unique among fresh-water 

 fishes ; it is comparable to the secretion of slime by the genital ducts of 

 amphibians during the breeding season. J. A. T. 



Study of Malagasy Perch. — J. Legendre (Comptes Rendus, 1918, 

 166, 617-9) has made a study of Parcitilapia polleni Blecker, one of 

 the Cichlidfe. It lives in lagoons, lakes and marshes with much vegeta- 

 tion, but neither in rivers nor canals. Tlie colour of the adult is very 

 variable and is adjusted to that of the surroundings. After the parent 

 fishes have sojourned together for a fortnight in a chosen corner, the 

 eggs are laid in a sort of nest. They are guarded thereafter by one 

 parent, probably the male. At least a thousand minute eggs are laid ; 

 the incubation lasts about fifteen days ; the developing eggs are very 

 black ; the larvae suggest tadpoles. Buccal incubation, which is common 

 in Cichlidfe, does not occur, but the nest is courageously guarded. 



J. A. T. 



Anomalous Pelvic Fins in Cottus bubalis. — Jean Delphy (BidL 

 Soc. Zool, France, 1918, 42, 118-21, 3 figs.) discusses remarkable 

 cases of atrophy. In the first there was coalescence, so that there 

 seemed only one fin. Perhaps there was some arrest of development at 

 an early stage. In the second case there was a reduction of one 

 fin almost to a vanishing-point — perhaps the outcome of an early 

 accident. J. A. T. 



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