152 THE JOURNAL OF INDIAN BOTANY. 



Finally, the substance of the mother-cells is divided into tetrads of spores 

 by invaginations, as in animals, regardless of whether the spindle fibres per- 

 sist or have already disappeared. No cell plate formation in the usual 

 manner has been observed. As the pollen grains are maturing, the tapetal 

 cells disorganize into a tapetal Plasmodium, a condition regarded as un- 

 common for angiosperms. 



The paper leaves one with the feeling that the author has distinctly fur- 

 thered our knowledge of the process of reduction, and of the mechanics of 

 heredity. The closing sentence is one the spirit of which might well be taken 

 to heart by all engaged in scientific investigation ; " it is considered that the 

 study of variations in the behavior of the chromosomes has been too much 

 neglected, and that any account is incomplete which does not include a record 

 of the conditions rarely or infrequently observed, as well as of those which 



seem to fall into the usual order of events." 



W. D. 



Distribution. 



Hitchcock, A. S., Floral aspects of the Hawaiian Islands. Annual 

 report of the Smithsonian Institution, 1917. p. 4J-9* (Just received). 



This is a semi-popular account of the flora of these islands and 

 contains much interesting matter. The writer is much struck with the 

 number and variety of ornamental plants which he met at Honolulu, 

 practically all of foreign origin. He states indeed that at least on the 

 plains, the native flora has been almost exterminated by introduced 

 plants, many of them weeds. This is in accordance with Charles Darwins 

 expectation of the superiority of continental and widely distributed species 

 over those of a small area. Among these introduced plants are several 

 species familiar to us in Indian gardens, e,g., Cassis fistula, C. nodosa, varie- 

 ties of Hibiscus, Acalypha, Aralia and the common Croton (Uodiaeum 

 variegatum) and of course the S. American Bougainvillea. The islands have 

 not escaped those pestiferous weeJs, Opuntia, and Lantana, but Acacia 

 farnesiana and Lucaena glauca, though introduced some years ago and 

 throughly naturalised have not become troublesome. Coming now to the 

 natural or indigenous flora, the most striking are the giant Lobelias, of which 

 there are as many as 100 species, some attaining a height of 40 feet. Ferns of 

 all sizes abound, the tree-ferns running up to even 30 feet, though usually 

 shorter. What is apparently a strongly zerophytic plant is the " silver sword", 

 Argyroxiphium sandwicense, which has numerous sharp pointed leaves 

 covered with silvery-white closely appressed wool. The plants grow in 

 dense tussocks from a few inches to two feet in diameter, on cinder cones 

 and other arid spots, and in the distance look like sheep. Similar tussocky 

 plant are common in other desert regions. An interesting feature of the 

 flora is the poverty in species of certain world-wide families. Thus there are 

 practically no orchids, only three small terestrial and rare species being 

 known ; the palms are represented by ten species only of the single genus 

 Pritcardia ; the Melastomaceae are entirely absent though so abundant in 

 tropical America ; and the Compositae and Labiatae, large universally distri- 

 buted families, and the former usually abundant in mountainous country, 

 have only a few species. Considering the tropical position of the islands, 

 and the large climatic differences caused by the presence of mountains 



