May 12, 1922] 



SCIENCE 



517 



In the fourth and fifth articles (Taf. XIX- 

 XXI) the author continues his already exten- 

 sive studies on the spermatozoa of various 

 animal groups, under tke titles "Die Spermien 

 der Cyclostomen" and "Noch einige Beitrage 

 zur Kenntnis der Spermien bei den Affen," 

 respectively. 



"Die Grehirne der Affengattnngen Cebus und 

 Ateles" is without figures. It consists of some 

 notes which supplement the author's earlier 

 work, "Das Aft'enhirn in bildricher Darstel- 

 lung," in which flgui'es of these brains are 

 found. 



The final contribution "Die Verbindungen 

 zwischen dem Sarcolemma und den Grund- 

 membranen der Muskelflbrillen in bildricher 

 Darstellung" (Taf. XVII, Fig. 25-27) is made 

 up of three figures which represent the striated 

 muscle of salamander larva3, showing the finer 

 structure of the muscle fibers and the relation 

 of the ground membrane to the myofibrillse and 

 to the sarcolemma. Apparently a paper on 

 this subject was contemplated by Retzius, but 

 the text was not written. The editor refrains 

 from supplying it, stating "Die Bilder demon- 

 strieren selbst so gut diese Verhaltnisse dass 

 sine eingehende Erkliirung nicht notig ist. 

 Prinzipiell will ich hier nicht versuchen, Worte, 

 die Retzius nicht selbst niedergeschrieben hat, 

 ihm in den Mund zu legen." This statement 

 admirably summarizes the attitude of the editor 

 toward the contents of the entire volume. 



The volume closes with an excellent table of 

 contents of the two series of the Biologische 

 Untersuchungen, namely, the two volumes 

 which appeared in 1881 and 1882, and the 

 nineteen volumes of the Neue Folge. Follow- 

 ing this is a bibliography of the scientific works 

 of Retzius, arranged by subjects. This bibliog- 

 raphy consists of 333 titles. 



It is fitting that the dedicatory page which 

 in the preceding volumes has borne the names 

 of so many distinguished anatomists should 

 bear in the last volume the inscription by the 

 widow of the author: 



Dem Andenken meines verewigten Gemahls 

 GUSTAF KETZIUS 

 in Liebe und Dankbarkeit gewidmet. 

 Anna Hierta-Eetzius. 



To the sympathetic cooperation of his wife 

 is due in no small measure, together with his 

 own untiring zeal, the unique monument which 

 Retzius has left in the nineteen folio volumes 

 of the Biologische Untersuchungen, and the 

 numerous other papers and monographs which 

 bear his name. 



0. Laesell 



Umiveksity op Oregon 

 Medical School 



SPECIAL ARTICLES 



POLYPLOIDY, POLYSPORY, AND HYBRIDISM 



IN THE ANGIOSPERMS 



For some time investigations have been car- 

 ried on in these laboratories on the subject of 

 polj^jloidy in relation to polyspory and hy- 

 bridism. The material used consists of both 

 Dicotyledons and Monocotyledons, and repre- 

 sents either known hybrids or species belonging 

 to genera or groups in which a great deal of 

 natural hybridism is suspected. The conclusion 

 has been reached that polyploidy is a common 

 result of incompatible species crosses. The 

 normal gametophj'tic number of chromosomes 

 becomes multiplied by three, four, etc., as 

 a consequence of such inharmonious crosses, 

 in various degi'ees of complexity. A fi-equent, 

 although not invariable accompanying feature 

 of polyploidy is the phenomenon of polyspory. 



As is well known, the normal divisions tak- 

 ing place in the spore-mother cells of the Angio- 

 spenns, lead to the formation of four spores. 

 Some of the members of the nonnal tetrad of 

 spores may exceptionally abort, as for example, 

 in the microspoi'es of certain sedges'. This 

 condition of abortion is the nonnal one in the 

 formation of megaspores. In the case of poly- 

 spory the first division of the spore-mother 

 ceU leads to the foi-mation of more than the 

 two normal daughter nuclei. Two larger nu- 

 clei are generally formed by the union of cer- 

 tain of the chromosomes which undergo sepa- 

 ration into daughter groups at a moment pre- 

 ceding that in which the remaining chromo- 

 somes pass into the metakinetic phase. The 

 later dividing chromosomes, in separating 

 tardily into daughter groups are ordinarily 



