Fortpflanzung. 65 



Fortpflanzung. 



171) V. Berenberg-Gossler, H., Über gitterkapselartige Bildungen in 

 den Urgeschlechtszellen von Vogelenabryonen. In: Anat. Anz., Bd. 40, 

 Nr. 21, 22, S. 587—591, 1912. 



Eingehende Beschreibung von Mitochondrien in den Urgeschlechtszellen. Es 

 handelt sich um ein Knäuel ziemlich dünnei-, mit Eisenhaematoxylin glänzend 

 schwarz gefärbter Fäden, welche meist miteinander netzförmig in Verbindung 

 stehen. Sehr häufig sieht man freie Enden in das umgebende Plasma hineinragen. 

 In dem Innern dieses Knäuels liegt die Sphäre, die somit von den Fäden umgriffen 

 ■wird. Die Lage, welche dieser Plasmakomplex im Innern der Urgeschlechtszellen 

 einnimmt, ist eine ganz bestimmte. Er liegt auf einer Linie, welche durch die 

 Mitte des Kernes und den breitesten Teil des den exzentrisch liegenden Kern 

 umgebenden Plasmamantels hindurchgeht, also auf der „natürlichen Achse" oder 

 dem Radius vector nach der Heidenhainschen Nomenclatur. Po II (Berlin). 



/ 



172) "VVilke, A.j Zur Frage nach der Herkunft der Mitochondrien in den Ge- 

 schlechtszellen. In: Anat. Anz., Bd. 42, Nr. 20|21, S. 499—506, 1912. 



Die Frage nach dem Ursprung der Mitochondrien wird auf Grund der Untersu- 

 chungen der Spermatocyten aus dem Hoden der Katze in der Weise entschieden, daß 

 ■die Plasmaursprungstheorie der Mitochondrien die größte Wahrscheinlichkeit besitzt. 



Po 11 (Berlin). 



173) Lewis L.L., The Vitality of Reproductive Cells. In: OklahomaAgr. 

 Expt. Stat., Bulletin 96, S. 1—47, 1911. 



Gives data from post-mortem examinations at definite intervals after Ser- 

 vice in swine, as to the vitality of spermatozoa and ova in the female genital 

 tract. The author's conclusions regarding sperm are as follows: "In only three 

 cases in the experiments of 1908 — 1909 could live sperm cells be found at a 

 greater length of time than twenty hours after breeding. In two cases live cells 

 were found after a lapse of more than forty hours, and in one case after a lapse 

 of twenty-two and one-half hours. Of the nineteen sows bred and killed, the 

 sperm cells were found dead in 80 percent of the cases examined where a period 

 of sixteen hours or more had elapsed between the hour of service and the time 

 ■when killed for examination." 



Regarding the vitality of the ovum the following statement is made: "If, 

 as previous observations seem to show, the egg cell is not liberated from the 

 ovary until near the close of the period of heat, and more than 70 percent of 

 the breeding is without results when service is given within twenty-four hours 

 after the period of heat, and no results follow from breeding at a later day, it 

 would seem that the ovum or egg does not retain its vitality for more than a 

 few hours after being liberated from the Grafian follicles." 



Some interesting experiments were made with stallions in regard to the 

 effect of continued (daily) service upon the number and vitality of spermatozoa 

 in the semen. A typical experiment of this sort gave the following results: The 

 semen from a service at 8.30 A. M., Feb. 13, 1908, gave 131750 spermatozoa 

 per mm^ of semen, and 20 percent of the spermatozoa were alive 9.5 hours 

 after service (kept at 21 — 23*^0. in vitro). The stallion performed service on 

 each of the eight following days. The service of Feb. 21, 1908, yielded semen 

 having 5840 spermatozoa per mm^, and no cells were alive after 4.5 hours 

 (21— 230c.). Pearl (Orono). 



Zentralblatt f. Zoologie, allgem. u. experim. Biologie. Bd. 3. 5 



