142 BOTANICAL GAZETTE [febrxjary 



endosperm nucleuSj which is fertilized by the second male nucleus, divides near 

 the lower end of the sac, and following this division the protoplasm is separated by 

 a plasma membrane into a large upper and a small lower cell. After two more 

 divisions in the lower cell, walls appear, and four basal endosperm cells are formed. 

 These elongate and divide again to form eight cells with dense contents which form 

 a cap over the lower end of the more extensive endosperm tissue above. This 

 lower tissue, while not so extensive, is similar in origin to that recently described 

 in the Pontederiaceae. After examining the food-stuffs of the seed, the author 

 closes with a description of a special tissue formed from the funiculus, which serves 

 to separate the seed from the placenta. — ^W. C. Coker. 



Roots of aroids. — Linsbauer^^ has studied the growth and geotropism of the 

 aerial roots of a large number of aroids. These are often dimorphic; some roots 

 are long and strong, the so-called Nahnmirzel (here called long roots) ; others are 

 more slender, usually horizontal and tufted, the Hajtimirzel (here called short 

 roots). Of these only a few have been sufficiently examined since the rise of the 

 statolith theory of geoperception. He extends Sachs's observation as to the great 

 length of the growing zone; in long roots for most it Hes between 20 and 50 

 with a minimima of 5-10^"^ and a maximum of 90"^^; in short roots, however^ 

 it runs from 3-14"^'^. Yet the former grow less rapidly than the latter; nor do 

 either grow daily more in toto than ordinary soil roots, and their growing zone is 

 not so sharply marked. The typical long roots are mostly geotropic, though only 

 weakly so, for in a whole day they do not curve from the horizontal to the vertical; 

 and many, even under the most advantageous external conditions, are wholly 

 or periodically ageotropic; typical short roots are always ageotropic. 



When the roots are not dimorphic (as in Anthurlum and some other genera), 

 tiiey are ageotropic. Both sorts have a well -developed columella in the root 

 cap, which is furnished, so long as they are growing, with statolith starch, quite 

 irrespective of their geotropic or ageotropic behavior. This fact LinsbatteR 

 contents himself with stating and does attempt to use It against the theory or to 

 reconcile it therewith. — C. R. B. 



mm 



Production of diastase. — Eisenberg has attacked anew the problem of the 

 regulatory production of diastase, determining the effect of various factors on its 

 formation." This was estimated by the effectiveness of a given solution in con- 

 vertn^ into sugar a standard solution of soluble starch. The results coincide m 

 large measure with those of previous observers and strengthen the belief that dias- 

 tese is formed in variable amounts according as other metabolic factors vary- 

 Thus more diastase is produced in active, less in sluggish, germination. At the 

 optiminn temperature for growth diastase production is greatest. In germinating 



i^ Li^SBAtnia, K., Ueber Wachstum und Geotropismus der Aroideen-Luftwur- 

 zeln. Flora 97:267-297. 1907. 



" Eisenberg, Eljride, Beitrage zur Kenntnis der Entstehungsbedingungen 

 diastatischer Enzyme in hoheren Pflanzen. Flora 97:347-374- J9°7- 



