GG MB. CROCKER ()N THE GERMINATION OF CYRTANDREiE. 



inch in length, fusiform, and taper to a point at each end. The 

 cotyledons are quite equal in size while enclosed in the seed, and 

 for the first few days after germination, which usually takes 

 place in about a week from the time when they are sown. Soon 

 after bursting the testa, which is usually carried up attached to 

 one of the cotyledons, these assume a greenish colour. They both 

 grow in an equal degree for the first few days ; but by the end of a 

 week, one has increased to more than double the size of the other, 

 and this still continues to grow until the plant lias reached the size 

 above mentioned. In fact, no other leaf is generally produced ; 

 out of several dozen plants I have examined, there has not been 

 the slightest attempt to produce a plumule. In one or two in- 

 stances, I have observed a small abortive leaf produced in the 

 sinus of the large coty]edonary leaf; this is always in a reversed 

 position, and does not become more than an inch in length. 



This peculiar mode of growth, although best seen in the plant 

 above mentioned, is, to a certain extent, exhibited in some other 

 and nearly-allied species, particularly in Streptocarpus (Didi/mo- 

 carpus) Bcxii and S.biflorus. Both of these produce two or three 

 true leaves, which are, however, smaller than the one enlarged and 

 foliaceous cotyledon, which is much developed, and in S. biflorusis 

 always double the size of any of the leaves afterwards produced. 



All the plants above named are natives of the southern part of 

 Africa ; it would be interesting to follow out the inquiry, and 

 see whether the same peculiarity is shared by members of the 

 Order from other countries. Some seeds of Ghirita Moonii sent 

 by Mr. Thwaites, of the Botanic Garden, Peradenia, Ceylon, to 

 Dr. Hooker, appear to exhibit it, but in a much less degree. The 

 cotyledons are quite equal at first ; but I see that after a week 

 or ten days' growth one of them is about a third larger than the 

 other. The plants of this division of Gcsncracece abound princi- 

 pally in the humid valleys of the eastern tropics ; and among 

 them are several monophyllous species, which, judging from 

 analogy, may be expected to follow the same plan of growth as 

 Streptocarpus polyanthus. Unfortunately they have not yet been 

 introduced into our European gardens. 



Descripttox of Plate IV. 



Fig. 1. ^Streptocarpus polyanthus. Seeds (about -^ in. long), and embryo with 



its testa removed. 

 Fig. 2. S. Sexii. Germinating embryo, removed from the testa, which i< was 



about to burst ; the cotyledons nre tinged green. 



