1174 Journal of Applied Microscopy 



CURRENT BOTANICAL LITERATURE. 



Charles J. Chamberlain. 



Books for review and separates of papers on botanical subjects sliould be sent to 



Charles J. Chamberlain, University of Chicago, 



Chicago, 111. 



REVIEWS. 



Juel, H. 0. Beitrage zur Kentniss der Tetra- This important contribution really 

 denbildung. Jahrb. f. wiss. Bot. 35: 626- consists of three distinct papers, which 



659, pis. 15-16, 1900. r r > 



can be considered separately. 

 I. Tetrad formation in the ovule of Larix. 



The homologies between the reproductive organs of the vascular cryptogams 

 and the phanerogams have long been known in their grosser features. The 

 pollen chambers in the anther are microsporangia and the pollen grains are 

 microspores. The ovule is a modified megasporangium and the embryo-sac is a 

 megaspore ; but while it is accepted that the pollen grain, like the spore of a 

 vascular cryptogam, arises by a tetrad division, it is generally believed that the 

 embryo-sac is formed without a tetrad division. 



Dr. Juel investigated the ovule of Larix sibirica from an early stage in the 

 development of the mother cell of the megaspore up to the beginning of endo- 

 sperm formation. The paper is of particular interest because it is the first to 

 treat this portion of the life history of a Gymnosperm from the standpoint of 

 modern cytology. 



In material collected about the middle of April, before the snow had disap- 

 peared, the mother cell of the megaspore was easily distinguished by its large 

 size and by the abundance of starch which it contained. The first division is 

 heterotypic and shows the reduced number of chromosomes (12). At the poles 

 of the spindle are granular masses which may possibly represent centrosomes. 

 During the anaplase the starch disappears, a cell wall is formed and each of the 

 daughter nuclei divides again by a homotypic division and thus gives rise to a row 

 of four megaspores, the lowest of which germinates and produces the prothallium. 



By comparing these series with the development of the microspore from the 

 mother cell, which has already been thoroughly studied in Larix, Prof. Juel comes 

 to the conclusion that the two series are homologous, the megaspore arising like 

 the microspore by a tetrad division. While this conclusion is not new, the evi- 

 dence supporting it is a real contribution. 



//. The tetrad division in a hybrid plant. 



It has long been known that hybrids are generally sterile, and it has also 

 been known that the pollen of hybrid plants is commonly imperfect. The pres- 

 ent writer investigated the formation of the tetrad in Syringa rothomagensis, a 

 hybrid between S. persica and S. vulgaris. The form did not prove to be a favor- 

 able one for such a problem, because the pollen of both parents is poor, in S. 

 vulgaris about 50 per cent, of the pollen grains appearing to be incapable of 



