322 M. Miiller on the Germination of Isoetes lacustris. 



any very great difficulty at New Norfolk river : it would require 

 only to take or kill a female Ornithorhynchus at the latter part of 

 September, and repeat the capture of other females during each 

 week of the months of October and November, or in December if 

 the specimen taken at the end of November was still pregnant. 

 The hinder half of each of such specimens, with the female organs, 

 or simply the impregnated uterus, should be preserved in strong 

 colourless spirits ; and if this should meet the eye of my esteemed 

 correspondent Mr. Ronald Gunn, or of Dr. Casy, I would ear- 

 nestly solicit their kind co-operation in transmitting such speci- 

 mens to me at the Royal College of Surgeons, London. 



XXXV. — An Account of the Germination of Isoetes lacustris. 

 By Karl Muller*. 



[With two Plates.] 



[Continued from p. 188.] 



6. Formation of the Third Leaflet. 



In order to make the appearance of the third leaflet particu- 

 larly clear, I have given an illustration of the development of a 

 single individual up to this point, as it may be seen either by the 

 unassisted eye or under a lens ; the embryos of fig. 24 a-g re- 

 present this. I do not think it necessary to enter again upon 

 the details of the earlier stages, and I pass now at once to the 

 actual appearance of the third leaflet. 



After I had made many conjectures as to the point where this 

 leaf would appear, it was formed, in the most fitting place, in 

 the middle, between the first and second leaves. Like these two 

 it issued gradually as a very delicate cone, the cells of which 

 speedily became more firm the more it came to light. The 

 formation, as a whole, had nothing else particularly striking 

 about it. 



I was now extremely anxious to know how the third root would 

 be developed. With all my many embryos I have not attained 

 the satisfaction of becoming acquainted with this point, since all 

 died in this stage. I here communicate my experience of the 

 rearing of Isoetes to botanical gardeners, in order to spare them 

 the vexation of seeing their young, hopeful crop all die away in 

 this stage. Success will be most surely attained by using a glass 

 of considerable size instead of a pot ; which must be filled pretty 



* Translated by Arthur Henfrey, F.L.S., from the Botanisehe Zeitung, 

 May 5, 1848. 



