Cytologie und Befruchtung. 2(31 



The second part of the book deals with the application of 

 general methods to the specific needs of the great plant groups. 

 The fact is recognized that it is difficult, especiaily for a 

 beginner, to apply general principles to specific cases. 

 Representative types, therefore, are chosen and detailed directions 

 are given, in many cases the most suitable thickness of sections 

 being indicated. the chapter dealing with spermatophytes is 

 the most elaborate, as it is in this group that the greatest 

 difficulties are encountered. W. J. G. Land. 



Ferguson, Margaret, C, The Development ot the Egg 

 and Fertilisation in Püiiis Strobiis. (Annais of Botany. 

 Vol. XV. p. 435—480. PI. XXlIl— XXV.) 



The autress describes the formation of the oosphere, the 

 process of fertilisation, and the segmentation of the tgg in PI/ms 

 Sirobus up to the the stage at which eight nuclei lie in its 

 basal region. 



The archegonia are formed at the micropylar end of the 

 prothallium about a fortnight prior to fertilisation. The neck 

 is usually one-layered, and consists of four cells, biit occasional 

 variations vvere observed. The form.ation of the ventral canal 

 cell was followed in great detail. During the mitosis the spindle, 

 at first multipolar, becomes more or less bipolar, and twelve 

 chromosomes are developed within the nucleus. No structures 

 resembling centrosomes, are present in this, or any succeeding, 

 mitosis. After the Separation of the ventral canal cell (which soon 

 disintegrates), the nucleus of the oosphere takes up a more 

 central Station, whilst the socalled „proteid vacuoles" make 

 their appearance in the cytcplasm. After some disciission as to 

 their probable origin, it isconcluded that they are derived from the 

 nucleolus of the nucleus of the oosphere and also from those 

 of the cells which sheath the archegonium. 



During fertilisation, all four nuclei pass from the pollen tube 

 into the oosphere, and the larger generative nucleus travels to 

 that of the egg, and comes to lie in a depression in the latter. 

 The other smaller generative nucleus together with the 

 vegetative one may show signs of mitosis, but ultimately they, 

 likc that of the stalk-cell, break up and disappear in the cyto- 

 plasm of the egg. 



The male and female nuclei do not hise, and their chromatic 

 Clements are distinct diu-ing the prophase of the first and 

 second divisions, though in the later phases they cannot be 

 separately rccognised. 



When four nuclei have been formed, these travel to the 

 base of the egg, and there divide to give rise to two stories 

 each containg four nuclei. Then the first cell walls appear, 

 and they are stated to arise by the conversion into cellulose of 

 a denser substance which lies between the nuclei. Other species 

 of -pines were compared with P. Strobiis, viz. P. austriaca, P. 



