Varietäten, etc. — Physiologie. 179 



Standish, L. M., What is happening to the hawthorns? 

 (Journ. of Heredity. VII. p. 266—279. 1916.) 



Among the Crataegi an extraordinary amount of comparatively 

 recent multiplication of forms is found; also large numbers of local 

 species combined with unusual sterility. Out of the 171 specimens 

 examined only thirty-five could be considered uncontaminated with 

 regard to pollen conditions, while seventy-six showed from 50 to 

 100% of abortive grains. Sterility partial or complete of the 

 reproductive cells has long been recognized as a characteristic of 

 hybridism; and forms which are ordinarily accepted as species 

 frequently reveal past genetical contamination by polleninfertility. 

 Among the Rosaceae, a family showing an unusually strong tendency 

 to hybridize, examination of the pollen conditions discloses a great 

 number of these hidden hybrids. 



The Intricatae on account of their unique position seemed worthy 

 of study in this connection. In the first place they are a relatively 

 new group so closely allied to the Coccineae that they are included 

 in the group as far as they were known to the older systematists. 

 They show a smaller ränge of distribution both collectively and 

 individually than do the Coccineae; they only occur in localities 

 where there is a possibility of crossing; and they have a degree 

 of sterility unusual even for the genus Crataegus. This seems a 

 suspicious combination of facts. Investigation of the other groups 

 in so far as the writer could get material, parallels the condition 

 found in these two groups — that among the more widely distributed 

 species the pollen is apt to be good, while in those of more local 

 ränge the pollen is largely abortive. This evidence is exemplified 

 by C. Venusta — a form extremely local in its ränge and growing 

 under circumstances ideal for cross fertilization — which proved 

 to be 750/0 sterile. 



The study of this genus has brought out evidence of both 

 systematic and morphological character to indicate the wide-spread 

 occurrence of hybridism; we must face the fact that among the 

 Crataegi at least extreme variability is linked with extensive 

 hybridization and the consequent multiplication of species, rather 

 than with mutation and the problem of the saltatory origin of 

 species. M. J. Sirks (Bunnik). 



Cook, O. F. and C. B. Doyle. Germinating coconuts. (Journ. 

 of Heredity. VII. p. 148—156. 1916.) 



The writers gave this summary at the end of their paper: 



The unique habit of the coconut of preserving a supply of 

 water in the interior cavity of the seed, the very large amount of 

 stored material or meat, and the very thick, tough, librous husk 

 are features that afford an extremely interesting example of speciali- 

 zation to assist in the germination and growth of the young plant. 



The cotyledons of the germination nuts show considerable 

 Variation in shape, and also in the markings on the surface. Some 

 of them have rather shallow, parallel ridges, while others are 

 deeply and irregularly furrowed. 



The formation of a soft, watery, superficial layer on the endo- 

 sperm after germination begins indicates presence of an active 

 fat-splitting principle in the milk, which partly digests the meat 

 and transforms it into such a condition that it can be readily 

 absorbed by the growing condition. M. J. Sirks (Bunnik). 



