OF FERNS FROM THEIR SPORES. 129 



cellules, shown in Suminski's figures (pi. 2. figs. 12-16), are, like those of the antheridia, 

 derived rather from the imagination than from fact. 



But the most important errors occur in the account of the development of the arche- 

 gonia. The earliest stage, as seen by looking directly upon the (under) surface of the pro- 

 thallium, was completely misconceived by Suminski. He overlooked the cell, forming 

 part of the general surface of the prothallium and becoming the parent-cell of the papilla, 

 which, from the first, lies between the embryo-sac and the external medium ; so that he 

 imagined the embryo-sac to be open and capable of admitting spermatozoids into its cavity. 

 I examined this point most carefully, and am convinced that he was in error. Any one 

 who looks at his figs. 1 and 2 of plate 3. will see that there exists no trace in them of a 

 cell or cells from which the papilla (seen from above in fig. 3 of his 3rd plate) could arise, 

 for the supposed orifice is bounded by seven cells, and if the papilla sprang from these it 

 would consist of seven vertical series instead of four. The fact is, that his fig. 1 of pi. 3, 

 stated to be from a dissection, merely shows what is seen in looking upon the under sur- 

 face of the prothallium, without dissection ; but it represents the object focused down to 

 the globule in the embryo-sac, as in my fig. 57, so that the membranes of the cells occu- 

 pying the space supposed to be an orifice and forming part of the continuous surface of 

 the prothallium (my fig. 56) are not seen. Fig. 3 of Suminski's 3rd plate shows a sub- 

 sequent stage, where the papilla, composed of four rows of cells, is already developed ; he 

 has missed the gradual production of this from the cell occupying the situation of the 

 imaginary orifice. 



This clearly takes away all ground from his hypothesis of the impregnation resulting from 

 the entrance of spermatozoids into the embryo-sac before the development of the papilla of 

 the archegonium, and moreover proves that the bodies contained in the closed canal of this 

 organ (shown in his figures, pi. 3. figs. 4-7) could not be altered spermatozoids. It will 

 be remembered that I have explained these appearances in a totally different way. 



With regard to the phenomena of the development of the germinal vesicle in the em- 

 bryo-sac, I think it is scarcely possible to obtain such clear views of the young structures 

 as Suminski has given, and I could only approximate to them by sections through the 

 prothallia, while from his figures we are led to suppose that he saw them through the 

 enveloping tissues, which are far too thick to allow such clear definition, especially since 

 their contents soon become coagulated by the injury the preparation suffers in water and 

 under pressure. All that Suminski states, therefore, respecting the development of a 

 cellule at the end of the spermatozoid, inside the globular cell of the embryo-sac, I regard 

 as the work of imagination, guided by a preconception of the necessity of some process 

 analogous to that described by Schleiden in reference to flowering plants, namely, the 

 production of the embryo from a cellule formed in the end of a pollen-tube, after the latter 

 has become imbedded in the embryo-sac. The drawings representing the subsequent 

 growth of the embryo are more or less incorrect ; thus the primary, undeveloped radicle, 

 which remains enveloped in the tissue of the prothallium, is not properly shown, while 

 this cellular tissue is represented as enveloping the base of the leaf and of the first adven- 

 titious root (pi. 4. fig. 10/. of Suminski's Essay), and the adventitious root itself as a 

 direct prolongation from the base of the first leaf. The true condition is shown in my 



