28 SUMMARY OF CURRENT RESEARCHES RELATING TO 



it is more like sebaceous matter without trace of horn. In some cases, 

 e.g. Lacerta agilis, there is an actual separation of material from the 

 mouth of the gland, quite apart from moulting. At the breeding season 

 there is in the males a specially active cellular modification in the 

 glandular body. 



The femoral glands arise from an insinking in the rete Malpighii 

 into the connective tissue, and a proliferation of the cells of the insunk 

 tissue. They may be called cytogenous glands — glandulse celluliparae — 

 and may be placed nearest sebaceous glands. 



c. G-eneral. 



Vital Rhythm.* — Messrs. Vaschide and CI. Vurpas deduce from 

 studies on the vaso-motor system, and from studies of abnormal cerebral 

 conditions (insanity, general paralysis, mania, anencephaly, &c.) that 

 life is characteristically rhythmic. There is a periodic alternation of 

 forceful action (" dynamogeny ") and repose. The higher nerve-centres 

 have the role of a psycho-dynamic co-ordinator, regulating the living 

 machine to a relatively stable equilibrium, in virtue of their superior and 

 quite specific property of inhibition. 



Comparative Anatomy of Vertebrates. f — R. Wiedersheim has 

 brought out a thoroughly revised (5th) edition of his well-known 

 Grundriss, with more figures, more bibliography, more summaries, 

 and necessarily more pages. In short, it is no longer a Grundriss, 

 but much more, and the Grundriss will be replaced by a smaller 

 work, an ' Introduction to the Comparative Anatomy of Vertebrates.' 



Colours of Fishes. J — D. S. Jordan contributes an interesting essay 

 on this subject. The colours of fishes are in general produced by oil- 

 sacs or pigment-cells beneath the epidermis or in some cases beneath the 

 scales. Certain metallic shades, silvery blue or iridescent, are due to the 

 deflection of light from the polished skin or the striated surface of the 

 scales. Certain fine striations give iridescence through interference. 



The ground colour is more subject to individual or local variation, 

 usually within narrow limits ; the markings are more subject to change 

 with age or sex, but are more distinctive of the species. 



The ground coloration most usual among fishes has protective value. 

 Protective markings are also common. In many cases the sexes are 

 differently coloured. Nuptial colours do not appear among marine 

 fishes, but are well known in minnows, dace, and some other fresh-water 

 fishes. 



Recognition marks, or what may be plausibly interpreted as such, are 

 frequent, and appear as ocelli, spots, cross-bars, and so on. 



In general, coloration is most intense and varied in certain families 

 of the tropical shores, and especially about coral reefs ; but the brilliancy 

 of individual markings of some darters (Etheostominse) and sun-fishes 

 (Centrarchidae) of the streams of eastern N. America is noteworthy. 

 The coral fishes seem to scorn the need of protective coloration, saving 



* Comptes Rendus, cxxxv. (1902) pp. 752-4. 



t ' Vergleichende Anatoraie der Wiibelthiere,' Jena, 1902, 8vo, xix. and GSti pp. 

 :and 379 figs. $ Amer. Nat., xxxvi. (1902) pp. 803-8. 



