1917] 



SPESSARD— PROTHALLIA OF LYCOPODIUM 



75 



Fig. 1 1 shows in detail the largest sporeling of L. annotinum grow- 

 ing from the prothallium represented in fig. 10. The sporeling of 

 L. clavatum shown in Fig. 12 was one of the largest, and serves to 

 indicate the size one may obtain still bearing the foot. It is very 

 possible, even for one who has studied carefully the figures of 

 Lycopodium prothallia given in the various papers upon the subject, 

 to mistake other forms of tubers for them. The sex organs may 

 be indistinct or undeveloped, so that identification by means of 



Figs. 18-21. Fig. 18, diagram of tissue regions in prothallium of L. clavatum 

 (antheridia and archegonia indicated) ; fig. 19, diagram of median region of prothallium 

 of L. complanalum, the fungus-infected region being indicated in this and fig. 18 by 

 dotted shading; fig. 20, detailed sketch of fungus-infected region, showing its location 

 beneath the epidermal tissue, X75; fig. 21, single cell with endophytic fungus coiled 

 within (fungus passes freely from one cell to another by piercing the cell wall), X750. 



them is impossible in such an instance. The number and variety 

 of small tubers which grow in the soil of a wood are both large and 

 confusing. Some of them are surprisingly similar in all outward 

 appearances to small prothallia of L. complanalum. I do not 

 doubt that I threw away some genuine specimens because they 

 appeared to be tubers. I know that I retained some tubers and 

 even sectioned them in paraffine because I thought they were 

 prothallia. 



