574 SUMMARY OF CURRENT RESEARCHES RELATING TO 



misinterpreted the facts. Collagenous fibres which represent a continua- 

 tion of the tendon-fibrils extend over the boundary line and spread out 

 on the muscle, but they have no continuity with muscle substance. 



Continuity of Muscle-fibrils and Tendon-fibrils.* — Oskar Schultze 

 re-affirms that he and Loginow have demonstrated the continuity of 

 myofibrils and tendon fibrils, and points out that with due care in tech- 

 nique anyone may convince himself. He answers the criticisms or con- 

 tradictions of Baldwin and Herwerden. 



c. General. 



Contraction of Melanophores of Fishes. t — R. A. Spaeth asks 

 whether the pigment-granules migrate in and out of fixed processes or 

 where these processes move like pseudopodia. Previous observers have 

 found that in crustaceans and amphibians the processes of the chromato- 

 phores are permanent. Spaeth finds that in the scales of the American 

 minnow, Fandulus heterocUtus, the migration of the pigment within the 

 melanophores may be completely controlled by appropriate mixtures of 

 sodium and potassium salts. It was thus shown that the processes of 

 the melanophores remain constant and that the apparent changes are 

 due to the movements of the melanin granules within the fixed processes. 

 This result is in full agreement with the conditions observed by Keeble 

 and Gamble in Macromysis, by Degner in Praunus^ and by Kahn and 

 Lieben in the frog. 



Gonads and Dentition. J — M. Robinson cites some cases which show 

 that early castration does not afPect the development or health of the 

 teeth. In a cryptorchid dog, however, with exaggerated endocrinal 

 secretion, the teeth were all black and brittle. Irritation of the genital 

 glands prejudices the teeth. Cases where all the teeth disappear quickly 

 sometimes show a complete atrophy of the gonads. A correlation of 

 gonads and dentition is maintained. 



Influence of Radium-rays on Germ Cells. § — Oscar Hertwig con- 

 tinues the investigation of the influence of radium-rays on germ-cells. 

 The spermatozoa of the newt can be aff^ected in various degrees accordinc^ 

 to the " dose," and the eggs which they fertilize are correspondingly 

 affected. Various sets of experiments have been conducted in Hertwig's 

 laboratory. Fertilized eggs of Ascaris, subjected for some hours to 

 radium rays, yield pathological nuclear figures ; they divide very slowly 

 and pass into karyolysis (Paula Hertwig). Spermatozoa of the sea- 

 urchin, subjected to radium-rays for several hours, may stimulate the 

 ovum to form a spindle, but may lose their power of forming normal 

 chromosomes and come to naught (Giinther Hertwig). > 



In the first and second cleavage of the frog's egg (Paula Hertwig) 

 and of the trout's egg (Oppermann), there is an elimination of the 

 sperm-nucleus which has been derived from spermatozoa subjected to 

 intense rays. Similarly, the radium-larva3 of the newt have been shown 



* Anat. Anzeig., xliv. (1913) pp. 477-9. 



t Anat. Anzeig., xliv. (1913) pp. 520-4 (3 figs.). 



X Comptes Rendus, clvi. (1913) pp. 2016-18. 



§ Arch. Mikr. Anat., Ixxxii. (1913) Abt. 2, pp. 1-63 (3 pis. and 4 figs.). 



