384 



BOTANY. 



Order Lycopodiacese. The prothallium is known only in one case, 

 viz., Lycopodiunt, annotinum. It was discovered underground by 

 Fankhauser in 1872, who described it* as a yellowish white, irreg- 

 ularly lobed body, sparingly furnished on its under surface with small 

 root-hairs (Fig. 274, A). In its upper surface the prothallium bears 



antheridia, which are 

 -^ "^ deeply sunken in its tis- 



sue (an, Fig. 274, A); 

 the spermatozoids.which 

 are numerous, are stout 

 and slightly twisted. 

 The archegonia were 

 only seen after the young 

 plants had grown con- 

 siderably (Fig. 274, B) ; 

 they are likewise devel- 

 oped upon the upper 

 surface of the prothal- 

 lium, and appear to bear 

 a considerable resem- 

 blance to those of the 

 Ophioglossacece. 



The young plant which 

 results from the growth 

 of the fertilized germ- 

 cell is quite simple, but 

 it soon takes on the form 

 of the mature plant. 

 The leaves are crowded 

 in Lycopodiuin, but are 

 Fig. 276 -Germination of the spores of Selaffinella. less so in the other gen- 

 1, longitudinal section of a macrosporc of >'. Mirten- _ j manv snwip"* 

 sii/ aWe the line d is the prothallium. below it the era ' 



" endosperm ;" ,', two embryos, the larger one with the sporangia are borne 

 its suspsusor projecting into the neck of the archego- . ,, nY :i a n t *!, _ 

 nium ; at the left of the larger embryo is a young ar- m the ax "8 of the or- 

 chegonium ; several root-hairs are also shown. 2, a dinary leaves, but in 

 voiing archegonium of the same species, not yet open. ,, ,, , , . , 



3, an archegonium of the rame species, with the germ- others the leaves which 

 cell fertilized and divid. d into two. A, a microspore bear sporangia are col- 

 of S. caulescens, rendered trans-parent, showing the di- , , . ... 



vision of the contents into the primordial cells; the lected into cone-like or 

 small lower cell is the rudimentary prothallinm. />, R nibfi like structures 

 later stage of the same, showing thelarge antheridium SplK6 ' " K6 Te8 ' 



filled with sperm-cells ; v, the rudimentary prothal- which terminate certain 

 Hum. All magnified.- After Pfeffer. branches (Fig. 275). The 



sporangia are more or less globose bodies, which are short-stalked 

 or sessile ; they contain large numbers of email spores, which escape 

 by an apical slit in the sporangium. 



* J. Fankhauser : " Ueber den Vorkeini von Lycopodium," in Botai- 

 iache Zeitung, 1873, No. 1. 



