348 Mr. A. Henfrey on the Progress of Physiological Botany. 



ment of the embryonary globule into an embryo. It must suffice 

 to state, that by the multiplication of cells it gradually enlarges 

 and acquires a definite form, producing a frond at one end and 

 a radicle at the other, bursts through the cavity in which it was 

 developed, and grows up, producing new fronds, into the charac- 

 teristic form of its species. These ulterior stages of the germi- 

 nation from the pro-embryo have been described by other au- 

 thors, although not so minutely, and our chief business is with 

 the new doctrine of the generation which has already been cri- 

 tically examined and contested. 



It must be mentioned here that the terms of Dr. Miinter's 

 report * are rather different from the above, which is important, 

 as he gives the facts as witnessed also by himself and Prof. Link. 

 He says with regard to the act of impregnation : — " Persevering 

 observations of these two essentially different organs gave the 

 following results. The spiral filaments emerged from the spon- 

 taneously opened hemispherical cells, two or three of them 

 moved rapidly toward the cup-like cellular protuberance, pene- 

 trated through the orifice into the still very short blind canal, 

 and then were converted into a little heap of mucus (schleim- 

 kliimpfchen) after their motion had ceased. After this {pften-oh- 

 served) process the quadratic orifice closed, and it was seen that, 

 in the blind end, one of the cells lying on the inside of the wall of 

 the semi-canal enlarged, and in it new cells originated.^^ 



This cell is said to be the embryo, which, elongating in a di- 

 rection at right angles to the canal, breaks through in two places, 

 one end producing a frond, the other a root. 



In the early numbers of the ' Botanische Zeitung ' for the 

 present year is contained a long memoir on this subject by Dr. 

 Albert Wigand, who, after extensive investigations, arrives at the 

 conclusion that the above-described process of impregnation does 

 not occur, and that the views of Count Leszczic-Suminski and 

 Dr. Miinter are based on errors of observation. His criticisms 

 would occupy too much space for the present article ; I shall 

 therefore reserve them for a future notice, and add to them some 

 observations of my own. 



In the ^Annales des Sc. naturelles^ for January 1849, M. 

 Thuret describes the antheridia or spiral-filament organs of Ferns, 

 but he does not appear to have detected the so-called ovules. He 

 also mentions that he has found similar spiral-filament organs on 

 the pro-embryo of the Equiseta. 



* Bot. Zeitung, Jan. 21, 1848. 



