Dr. Hanstein on Fecundation and Development in Marsilea. 417 



3. Mandibles falciform, with the inner margins smooth, but 



presenting impressions of denticulations ; outer margins 

 with a projecting haft (contre-furt). 

 A. erythrinus; A. falcarius ; A. Manticorus. 



4. Mandibles falciform, with the inner margins denticulated, 



and with no projecting haft on the outer margins. 

 A, Trigli; A. Scarites ; A. Lupi ; A. rapax ; A. verrucosus. 



XLV. — On the Fecundation and Development of Marsilea. 

 By Dr. Hanstein*. 



When the task was set me of reporting to the Academy upon 

 the capability of development of the so-called Nardoo-fruits 

 (the capsules of an Australian species of Marsilea). and upon 

 the processes observable in it, I was unable to trace either the 

 fecundation or the development of the germ-plant upon the few 

 fruits first sent by Alexander Rose, as nearly all the prothallia 

 remained unfertilized. Since then I have succeeded in repeated 

 sowings, for which fruits sent by Mr. Osborne, of Melbourne, 

 and by Dr. Ferdinand MUller, of the Botanic Garden at that 

 place, were employed, in witnessing the reproduction and germi- 

 nation of this genus, which were previously unknown. 



About four hours after the micro- and mcgaspores have es- 

 caped into the water in the manner formerly described by mcf, 

 and issued from their sporangia, the first alterations are per- 

 ceptible in them. In the small androsporcs the contents, of 

 starch and proteine-substance, have then formed a more homo- 

 geneous plastic mass, and become somewhat contracted all round 

 from the margin, leaving only a few granules on the latter. 

 This mass is then quickly divided, by three planes of segmenta- 

 tion perpendicular to each other, into eight e((ual parts, and 

 each of these is immediately broken up in two directions, differ- 

 ent froBi each other and from the previous directions of division, 

 into four parts, disposed in relation to each other in the manner 

 of the angles of a tetrahedron. In this way thirty-two equal 

 portions of protoplasm are produced by an act of division which 

 resembles the process of segmentation in the animal ovum ; and 

 it is only after the completion of this that a cell-membrane is 

 formed around each of them. 



In each of these thirty-two cells, which retain their regular 

 arrangement, a spermatozoid is developed. The four spermato- 

 zoids of each tetrahedral group lie in the approximated halves of 



♦ Translated by W. S. Dallas, F.L.S., from the * Monatsbericht dcr 

 Akademie der Wissenschaften zu Berlin, August 1861, p. 5/6. 

 t MonaUber. Berl. Akad. 1863, p. 414. 



Aim.b; Mag. N. Hist. Ser.3. To/, xiv. 27 



