and Laboratory Methods. 1175 



functioning, and in 6". persica normal pollen grains being quite rare. The latter 

 form is almost as sterile as the hybrid. 



In all three forms the development is normal up to the formation of the pollen 

 mother cells. In the hybrid S. rothomagensis it was found that while most of the 

 divisions in the pollen mother cells were mitotic, there were also numerous cases 

 of amitotic division, and abnormalities in the chromatin and in the achromatic 

 figure were frequent. 



///. The development of the pollen grain of Carex. 



As a rule the pollen mother cell of a flowering plant gives rise to four pollen 

 grains, but it has been reported that in the Asclepiadaceae and Cyperaceae the 

 mother cell gives rise to but one pollen grain. 



A careful examination of Carex acuta gave the following results : The wall 

 of the pollen mother cell becomes the wall of the pollen grain. The tetrad divis- 

 ions take place, but the walls separating the four cells are imperfect and only one 

 cell of the tetrad develops into a pollen grain, the other three being crowded out, 

 just as in the megaspore series three potential megaspores are crowded out by 

 the one functioning megaspore. c. j. c. 



Dixon, H. H. On the first mitosis of the spore ^^^ ^^^^or States very clearly the 

 mother cells of Libtun. Notes from the •' ■' 



Botanical School of Trinity College, Dublin, points in regard to which there is 

 No. 4, pp. 129-140, pis. 7-8, 1 90 1. essential agreement among cytologists, 



and outlines the debated questions. While admitting that there is still ample 

 room for dispute, he concludes that in both the first and second nucler divisions 

 by which the spores are formed from the mother cell, the splitting of the chro- 

 mosomes is longitudinal and that, consequently, there is no reducing division. 



c. J. c. 



Holm, Theodore. Erigenia bulbosa, Nutt. A Mr. Holm, who has done more than 

 Morphological and Anatomical Study. Am. ^^^ gigg j^ this country on the 



Jour. Sci. IV. II: 63-72. 6 figs. ^ ■' 



minute anatomy of plants, presents in 



his latest paper some interesting morphological and anatomical facts on this 

 unique plant. The Erigenia possesses a single cotyledon. The blade of the 

 cotyledon is held in a horizontal position and raised above the ground by a long 

 slender petiole. In the second year after germination the first proper leaf 

 appears and has a ternately decompound leaf, with divisions of the same shape 

 as those of the mature leaf. The third year's growth is not much advanced as 

 only a single green leaf is developed with a few additional divisions. The Eri- 

 genia germinates then with only one cotyledon. 



The tuber as it appears during the seedling stage, as Holm has shown from 

 anatomical consideratiohs, is a swollen part of the primary root. 



The structure in fully matured specimens is very different, and here is what 

 the writer says concerning this : 



" The mature tuberous root possesses a number of cork-layers, a secondary 

 bark of very considerable width, filled with starch, and inside the bark is a band 

 of collateral mestome-bundles with cambium between the leptome and hadrome 

 and besides well defined strata of interfascicular cambium, while a broad pith 



