164 INTRODUCTION TO CRYPTOGAMIC BOTANY. 



tion, that Robin asserts that in Ulva Lactuca two sporiform 

 bodies of different functions are generated, one of which germi- 

 nates, and the other, which is quadricihate, never does so. He 

 believes, moreover, that these last are truly spermatozoids. In 

 such minute bodies it is always difficult to speak with absolute 

 precision, and even giving full credit to the observation of 

 M. Thuret, that the biciliate bodies do sometimes germinate, 

 it does not follow that Rolnn's observations are devoid of truth. 

 It is certain, at least, in some of the AlgjE which follow, that 

 the ciliate bodies are not capable of germination, but truly of 

 the nature of spermatozoids. The Antarctic genus, Masioclia, 

 does not belong, properly, to this group, but will be noticed 

 hereafter among the gelatinous Lichens. Stigonema also 

 belongs to the same category. 



138. These Algae are distributed over the whole surface of 

 the globe, but they abound principally in colder latitudes, 

 Entero'niorplm intestinalis and Bangia atropurpurea grow 

 indifferently in fresh and salt water. The green species are 

 occasionally eaten, but it is Porphyra, more especially, which 

 supplies on rocky coasts, where there is not sand to make the 

 fronds gritty, the laver of commerce. The best way of pre- 

 paring this vegetable or condiment, which is extremely whole- 

 some, is to heat it thoroughly with a little strong gravy or 

 broth, adding, before it is served on toast, a small quantity 

 of butter and lemon juice, Enteromorpha intestinalis is used 

 in Japan, when dried, for soup. 



139. Some Algce, as Tetraspora, in which the gelatinous 

 element predominates, usually referred to Ulvacece, belong 

 more properly to Palmellece, in which highly compound 

 fronds are presented by Hydrurus. The genus Hormo- 

 spora, which occurs both in salt and fresh water, is a fila- 

 mentous Palmelloid. In H. ramosa, Harv. Phyc. Brit. t. 

 218, the threads, which are parasitic, on Cladophora fracta, 

 are irregularly branched. One of the most curious Algse, 

 perhaps, on record, is PsicJiohormium, described by Itzigsohn 

 in Flora, 1854, p. 17, and accompanied by a figure. It 

 is placed by Kiitzing next to Conferva, but its relation is 

 doubtful. The articulations are obscure, and it is, possibly, 



