558 Black : The imbedded antheridium in Dryopteris 



number of chromosomes, takes the place of the normal sexual 

 fusion of the two gametes. 



In addition to the above, the following ferns were studied : 

 Athyrium Filix-foemina^ vars. clarissiina Bolton, clarissiina Jones, 

 and nnco-glomeratujH Stansfield; Lastrea pseudo-mas, van crista fa 

 apospora Druery; and Scolopeudninn vulgaj^e var. crispuni Dnan- 

 mondae. From these five forms, being aposporous, naturally or 

 induced, there resulted prothallia having the double or sporophytic* 

 number of chromosomes. Different types of sporophytes were 

 produced from these aposporous prothallia, namely: from the pro- 

 thallia of Athyrium Filix-foemiiia, var. clarissima Bolton, and Scolo- 

 pendrimn vidgare^vdiV, crispiim Driimmondae, the embryo arose in 

 each case from an egg-cell, fecundation being unnecessary as the 

 egg-cell already possessed the full complement of chromosomes. 

 While the complete details were not made out for the origin of the 

 embryo produced in Athyriuui Filix-fo£jnina,\dx. unco-glouieratiun 

 Stansfield, the probabilities are that it is like the preceding'. The 

 two remaining forms are examples of sporophytic budding. In 

 Athyrium Filix-foemina, var. clarissima Jones, the sporophyte ap- 

 pears as the direct outgrowth of the apical surface in connection 

 with an endogenous foot. The sporophyte in Lastrea pseudo-mas, 

 var. cristata apospora Druery, makes its appearance as a small 

 excrescence directly behind the growing point. 



Lang ('98) presented a detailed account of the grosser phe- 

 nomena of apogamous sporophytic outgrowths from prothallia 

 grown from spores. The following fourteen forms are described : 

 Aspidium acnleatum Sw., var. midtifidiim Woll., A. angulare 

 Willd., var. foliosnm imdtifidiim, var. acutifolium midtifidum (no 

 results), A. frondosiim Lowe; AtJiyrium mpponiciipi Mett., var. 

 . aistatum, A. Filix-foemina Bernh., var. percristatum Cousens, var. 

 cruciato-cristatiim, var. coronatiim Lowe ; Nephrodium dilaiatum 

 Desv. var. cristatum gracile, N. Oreopteris, var. core nans Barnes ; 

 Poly podium indgare L., var. grandiceps Fox ; Sc elope ndriiim vul- 

 gare Sm., var. ramulosissi inn m Woll., var. marginale. His results 

 were obtained from experimental cultures of prothallia, watering 

 them only from below and exposing them to bright sunlight, 

 diminishing in this way the frequency of fecundation. The most 

 usual type of sporophytic budding cited in his paper is that of the 



