Entwicklung, Regeneration. 255 



stical evidence points to a differential natural increase as an important factor in 

 determining the present and future relative proportion of the white and negros 

 in the United States. Statistics of New England show that the native Americans 

 are dying out at a rapid rate. A comparison made between the cities of the 

 north and the country districts of the north, and the cities of the south and the 

 country districts of the south, indicates that in all main divisions of the United 

 States fecundity in country districts is greater than fecundity in cities. The pro- 

 pertion of sterile rnarriages for the various nativity classes of the foreign born 

 show that it is highest among wives born in Scotland or England, lowest among 

 wives born in Poland, Bohemia or Russia, but in none of these cases is it as 

 great as among rnarriages where the wives were born in the United States. 



Pearl. 



769) White, F. N., Variations in the sex-ratio of Mus rattus associated 

 with an unusual mortality of adult females. In: Proc. Royal Soc, 

 Bd. B. 87, Nr. 596, S. 335 — 344, 1914. 



In collecting and examining rats in connexion with plague -prevention in 

 India in 1911, it was observed that in Lucknow nearly all the young rats trap- 

 ped during the early summer were females, and that at the same time there was 

 a conspicuous deficiency of females among the mature rats. In other places no 

 such variations from the normal sex-proportions were observed. Tables are given 

 showing the numbers of each weight and sex of all rats caught in each month 

 of the year in several Indian towns. It is suggested that some undetermined 

 cause killed off a large proportion of the adult female rats in Lucknow in the 

 spring of 1911, that apparently in consequence an enormous excess of females 

 was born, and as the sex-proportions again became normal, the ratio of males 

 to females born also returned to normal. Doncaster. 



Entwicklung-, Regeneration. 



770) Lee, E., Observations on the seedling anatomy of certain Synipetalae. 

 II. Compositae. In: Annais of Botany, ßd. 28, Heft 2, S. 303—329, 1914. 



In this continuation paper the seedling anatomy of a large nuniber of Compositae 

 is studied and the results discussed. The results of measurements of the size of vascu- 

 lar structure reveals a lack of uniformity or constancy, so the conclusion is reached that 

 "other factors are at work in addition to those which are purely physiological". It is 

 believed that in addition to the physiological and environmental factors influencing 

 seedling anatomy are factors "connected with the nature of the organism". In the 50 

 species examined, the seedlings were all of the diarch or tetrarch type, and since vari- 

 ations in structure were found even in different members of the same species it is con- 

 cluded that "seedling anatomy is of no value in questions of affinity". It is believed 

 that instead of the vascular evolution of seedlings being a slow and conservative pro- 

 cess, tetrarchy and diarchy have probably been interchanged several times in the evolu- 

 tion of Angiosperms. There are many exeeptions even to the rule that size oi' seedling 

 is correlated with the type of structure. Gates. 



771) Keiser, \V., Untersuchungen über die erste Anlage des Herzens, 

 der beiden Längsgefäßstämme und des Blutes bei Embryonen von 

 Petromysou planeri. In: Jen. Zeitschr., Bd. 51 (N. F. 44), S. 579— 626, 

 30 Textfig., Taf. XI— XIII, 1914. 



Keisers Untersuchungen richteten sich auf die Klärung der Frage nach 

 der Herkunft der ersten Herzendothelzellen. In Übereinstimmung mit den ent- 

 sprechenden Verhältnissen bei Amphibien und Dipneusten fand der Verf., daß bei 

 Petromyson auch die Endothelien des Herzens und der Blutgefäße mesodermaler 

 Abstammung sind. Ebenfalls mesodermalen Ursprunges ist das Blut. Weiterhin 



