NOTES AND ABSTRACTS. 



(575 



The host-cell normally averages 15 /x in diameter. After the occupation 

 by the parasite it usually attains a diameter of 100 fx or more. The 

 authors then describe the vacuolisation of the nucleolus, the distribution 

 of chromatin in clots and droplets on the surface of the nuclear membrane, 

 in preparation for mitosis, when the membrane becomes gelatinous, the 

 chromatin assumes the spirem form, and the nucleolus disappears. The 

 chromatin undergoes remarkable changes. Formerly lumpy, it becomes 

 changed into more numerous and small masses, then elongate into rods 

 in an entangled manner. This is the spirem stage. The spirem threads 

 become thickened, apparently by longitudinal fusion of separate rods, 

 while the size of the nucleus decreases. 



A spindle now forms in the centre by the threads of the spirem group 

 forming themselves into the spindle. 



No centrosomes or polar radiations were distinguished in any stages of 

 the mitosis. 



The whole chromatin content has all along been decreasing largely. 



The nuclear membrane, after gelatinising, forms a broad zone of 

 granular matter, in the centre of which, within a clear space, the spindle 

 lies. 



The chromosomes appear to be four in number at each end. The 

 spindle fibres fall together in the centre and divide, giving rise to the 

 independent daughter nuclei. — G. H. 



Mole Cricket in Porto Rico. By 0. W. Barrett {Bull. Bot. Dep. 

 Trin. 39, p. 573). — Gives the best methods for combating this insect 

 pest, which is terribly destructive to crops of Tobacco, Cane, and small 

 crops. — E. A. B. 



Moles, A Plea for (Joum. Hort. August 20, 1903, p. 167).— It is 

 said that the mole, being insectivorous, is one of the farmer's best friends. 

 Also that he assists in dressing the surface with new soil, and draining it 

 by his tunnels. This is true enough, but those who have had experience 

 of moles in gardens, and especially on rockeries, will be willing to forego 

 these advantages. — C. W. D. 



Monocotyledons, A Theory of the Origin of. Founded on the 

 structure of their seedlings. By Ethel Sargent (Ann. Bot. vol. xvii. No. lxv. 

 pp. 1-89, Jan. 1903 ; plates i.-vii. ; ten figures in the text).— This paper is 

 the record of a very important and well carried-out investigation, the 

 direction of which has received but little attention. Its object has been 

 to throw light, if possible, on the relationship between Monocotyledons and 

 Dicotyledons. The index of species mentioned contains 159 names ; 12 

 species are illustrated by the 60 figures in the plates, all, with one excep- 

 tion, drawn by Miss Agnes Robertson. A generation ago the Mono- 

 cotyledons were regarded as probably the older group, but botanists have 

 never been unanimous in this opinion, and of late the evidence of fossil 

 botany has, on the whole, inclined the scale in the opposite direction. 

 The case is so admirably summed up by Professor Bailey Balfour (in the 

 article on Angiosperms, Supplement to the 'Encyclopedia Britannica,' vol. 

 xxv. 1902), that I am tempted to quote his judgment in full : 



