714 SUMMARY OF CURRENT RESEARCHES RELATING TO 



these ovaries, al though at different and ordinarily later periods, there also 

 appear special cells, which are the homologues of the iutermcdiate cells 

 of the testis. In some cases special structures, which are perhaps 

 analogous to the adrenals, are developed in connection with the medul- 

 lary cords. In all ovaries a large numher of follicles atrophy ; this 

 atrophy varies in various follicles, and especially with regard to the dis- 

 tribution of the cells of the granulosa. The impulse to atrophy ajipears 

 to arise in all cases from the connective-tissue cells of the three folliculi. 

 The membrane which incloses the egg seems to bo merely a product of 

 the grauulosa-cells. 



7. General.* 



Influence of Light on Oxidation.! — Hcrr J. Loeb has made a num- 

 ber of experiments with pui^as to test the influence of light on tho 

 processes of oxidation within the organism. He measured the variation 

 in the expiration of CO^ under diffei-ent conditions of illumination. 



There is no doubt that the light stimulus increases oxidizing pro- 

 cesses. This increase has its seat mainly in the muscles, but may bo 

 observed wiien there is no movement, as was the ease obviously in the 

 piipoe. Moleschott's opinion that the light influenced the muscles 

 throiigh the central nervous system, is confirmed. In the lower animals 

 the stimulus may be influential without the presence of eyes ; in mammals 

 light has no appreciable local influence in increasing oxidation ; this 

 is only to be observed in plants where the proportion of surface to 

 mass is so much greater. The results of the author's experiments are 

 summed u]) in two tables. 



B. INVERTEBRATA. 



Problematical Organs of the Invertebrata.| — Dr. A. B. Griffiths 

 has made a chemical and physiological study of some of the problematical 

 organs of the Invertebrata, and states the results as follows: — A. (1) 

 The nephridia of Cephalopoda are true kidneys; (2) the renal organs 

 of Astacus Jluviatilis, Anodunta cijgnca, Limax flavus, Helix aspersa, 

 and Periplaneta orientalis, are analogous in function to the renal organs 

 of higher animals ; (3) the renal organs of the Lamcllibranchiata and 

 Crustacea are true kidneys ; and (4) the " segmental organs " of the 

 Oligochieta and of the leech are renal in function. B. The " salivary 

 glands " of the Gasteropoda and Insecta arc similar in function to the 

 salivary glands of higher animals. C. The so-called " livers " of the 

 Gasteropoda, Lamellibranchiata, Crustacea, and Insecta are pancreatic 

 in function. 



Distribution of Striped Muscle.§— Prof. H. Fol discusses the dis- 

 tribution of striped muscular tissue in Invertebrate types. The distri- 

 bution of the two kinds of muscle in the difierent systems in Vertebrates 

 hardly holds good among the lower animals. In Coelenterates tho 

 striped tissue is only found in swimming forms, in the umbrella and 

 tentacles ; the same is true of Tunicata ; but most of the agile worm 

 types have only unstriped muscles. In the Arthropods, on the other 



* This section is limited to papers ■which, while relating to Vertebrata, have a 

 direct or indirect bearing on Inveitebrata also. 



t Arcli. f. d. gesammt. Physiol. (Pfluger), xlii. (1SS8) pp. 393-^07. 

 J Proc. Roy. Soc. Edin., xiv. (1887) p. 230. 

 § Comptes Kendus, cvi. (1888) pp. 1178-80. 



