Aloe. 283 



leaf we have, is thick, ovate-lanceolate, 26 cm. long, 9 cm. broad, 

 channelled in the upper fourth, with marginal prickles very short, 

 separated by irregular rounded inters[)aces. As a combination of 

 these characters seems to be sufficient to distinguish it from all 

 other known species of Aloe, I will call Zejdier's, No. 4176 



A. par viftpina, Schonl.xi.sp. 



Its affinities to ofher species are not quite clear to me. 



With the increased opportunities of studying the genus 

 I have been struck with the extreme variability of many of 

 the species in two directions. Firstly, there is no doubt that there 

 are many more or less constant forms which have been derived 

 from distinct species s. sir. These variations exist in nature as 

 well marked entities. But in addition, many species respond to 

 the slightest change in the conditions under which the}' are grown : 

 a change of soil ov a change of climate or both make them alter 

 their features, especially those of the vegetative organs, which are 

 usually looked upon as distinctive, to such an extent, that it is 

 practically impossible to characterise them sufficiently so that 

 others can i-ecognise them again. These second variations, which 

 unfortunately cannot always be distinguished from the first, 

 " represent no permanent lines of more or less independent 

 development in nature, but chance combinations of inconstant 

 characters analogous to cross-sections through some plastic and 

 still unsoliditied material '' (see B. L. Robinson, " Problems and 

 Possibilities of Systematic Botany," in Science, vol. xiv. No. 3")2). 

 The formation of hybrids under natural conditions has also to lie 

 considered. 



To determine the limits of the species accurately and to study 

 the problems bound up with this question, it will ultimately be 

 necessary to raise seedlings from seeds of wild plants on a very 

 large scale, and under varied conditions. Perhaps we raaj' not 

 arrive at such startling results as Mr. N. E. Brown described 

 (Gard. Chronicle 1878, pp. 820-822) in the genus Hawortki a, whevo 

 he found 6 plants from Mr. Cooper's collection of succulent plants 

 at Reigate representing 6 described '■ species," although they were 

 all raised from the seeds of a single capsule of Haworthia cvecta, 

 Haw,, yet the experiments would well repay the time and trouble 



