SUMMARY OF CURRENT RESEARCHES. 533 



anastomose. All vessels, except the aorta, arise as spaces in the mesen- 

 chymatous mesoderm. The surrounding cells form the walls. The 

 aorta arises from individually segregated mesoderm cells. Anteriorly 

 these form two vessels, posteriorly they form one, lying under the sub- 

 chorda. The anterior portion is established before the trunk portion. 



Reactions of Vertebrate Embryos.* — S. Paton describes some of 

 the primitive reactions of embryos of Amphioxus, various fishes, and 

 amphibians to environment, to incident stimuli, and to metabolic pro- 

 cesses. In relation to this there is given a general outline of the 

 development of the nervous system at certain epochs, followed by a 

 discussion of what seem to be the more important histological charac- 

 teristics of these periods. In general it may be said that the functional 

 activites of the body represented by the beat of the heart and the primi- 

 tive movements of ab- and adduction of the body begin at a time when 

 these phenomena may as yet neither be designated as myogenic nor 

 neurogenic in origin. In the case of the heart it is not at all improbable 

 that impulses may be conducted and even originate in the undifferen- 

 tiated tracts of protoplasm which exist. Neurofibrils have an important 

 bearing upon function. One of the chief histological characteristics of 

 the fully differentiated nerve is that it contains neurofibrils, and all the 

 evidence so far accumulated points to the appearance of these structures 

 as marking the period of greatest physiological activity in any given 

 nerve. A cell is not to be regarded as a nerve unless it contains 

 neurofibrils. 



Blastoporal Asyntaxy in Amphioxus.f — R. Legros discusses the 

 significance of asyntaxic development and its bearing on the theory of 

 concrescence. Material was found in embryos submitted to the action 

 of chloride of lithium, and in embryos obtained after retarded fertilisa- 

 tion. He concludes that " asyntaxic development and normal develop- 

 ment consist in the same total of the same cellular movements. The 

 principles of the theory of concrescence find their rigorous verification 

 in the method of closing of the blastopore and in the phenomena of 

 organogenesis which accompany anachronic notogenesis in the asyntaxic 

 embryos." He further regards it as demonstrated that the closing of the 

 blastopore and formation of the archenteric roof in the normal Amphi- 

 oxus are effected by concrescence. 



Histolysis and Histogenesis of Muscles of Ant Queen.l — C. Janet 

 has followed the histolytic changes which occur in the vibratory muscles 

 of the wings of ant queens after nuptial flight. Mesodermic free 

 cells — true leucocytes — accumulate around the degenerating muscles, 

 subsequently penetrating their envelopes, lifter penetration the leuco- 

 cytes become adipocytes or adipogenic bodies, transforming the muscle 

 substance into adipose tissue. 



Histology and Function of Calciferous Glands in Lumbricus.§ — 

 A. Combault has made a histological study of these glands. He describes 



* Mitt. Zool. Station Neapel, xviii. (1907) pp. 535-81 (3 pis.). 



t Tom. cit., pp. 440-534 (2 pis. aud 6 figs.). 



i Comptes Rendus, cxliv. (1907) pp. 1070-3 (22 figs.). 



§ G.R. Soc. Biol. Paris, Ixii. (1907) pp. 570-2. 



2 N 2 



