44 "^'ol. XI III, Alt. l.-K. Yendo: 



upper portion of a sporopbyll divides into two segments with broad 

 and round sinus. The resultant segments are sometimes of equal 

 value, but sometimes one of thorn appears as if ramified from 

 the other. 



Species which liave in normal condition smooth blades, may 

 sometimes be found with transverse corrugation along both sides 

 of the midrib. Examining closely we find generally in such case 

 numerous parasitic Crustacea, mostly of species belonging to Gam- 

 maridse, living in the midrib. The little creature digs a labyrinthic 

 tunnel through the medullary and subcortical tissue of the midrib. 

 This causes the retarding of the growth in length of the midrib. 

 As the blade is in no way infected by the parasite, the unequal 

 speed of growth in length of the two parts results only in the 

 corrugation. 



Development and Life History of Alaria, 



The recent investigations on the embryonal stages of A. escu- 

 lenta Geev. and some species of Laminaria by Drew,^) Killian,^) 

 Saüvageau,^) etc., have greatly changed the view hitherto held by 

 modern botanists on the life history of the Laminariaceous plants. 

 We are now aware that the zoospores liberated from the unilocular 

 sporangia of the sori of the Laminariaceae do not directly develop 

 into the well known, large forms of fronds, but germinate into 

 microscopic protoiiema-like bodies. The latter are sexual and 

 dioeceous, i. e., either male or female gametophytes. From the 

 oogonium an embryonal frond starts which may develop into the 

 large form commonly known as a Laminariaceous plant. Thus in 



1) DiiKW : Keproduction and Early Development of Lam. dljitala. 



2) KiLLiAN : Beiträge zur Kenntn. der Laminarien. 



3) Sauvageau : Sur les plantules de quelque Laminaires. 



