M. A. Biaun on the Nucleus of the Characeae. 301 



planation from Hofmeister's was proposed by Griffith*, and still 

 earlier, but less consequently, by Meyenf- Both compared the 

 fruit of the Characece to the ovules of the Phanerogamia, regard- 

 ing the envelope as integument, the central portion as nucleus. 

 Since the single generation of the Characese, as the producer of 

 spores, may be compared vriih the second generation of the Vas- 

 cular Cryptogamia, a comparison still further supported by the 

 fact that the entire mode of construction of the Characeaj by no 

 means belongs to the forms of thalloid structui-e, but exhibits a 

 definite contrast of stem- and leaf-formation, nothing can be 

 said a priori against seeking a comparison on this side. In the 

 gradual closing together of the central body, the envelope of 

 the C7mra fruit^ certainly exhibits a similar behaviour to the in- 

 tegument of the Phanerogamic ovule, and the comparison of the 

 central portion with the nucleus seems even still more apt. This 

 central portion, hitherto regarded as a single cell, is in fact a 

 cellular body fonned of four cells, one of which by prepondera- 

 ting growth at an early period displaces the rest, and may be 

 compared with the embryo- sac. It might appear as though no- 

 thing were wanting in this comparison but the formation of an 

 embryo in the large cell of the central body. But after close 

 examination, only a distant resemblance remains even on this 

 side ; for while the integument of the Phanerogamic seed corre- 

 sponds to a closed sheath-like leaf, the integument in C/iara, as 

 I shall demonstrate hereafter, is an envelope formed of a five- 

 leaved whorl. The greatest diflFerence however relates to the 

 nature of the large cell of the central portion, which, for compa- 

 rison either ^rith"the embryo-sac or with the central cell of the 

 archegonium, must be the mother-cell of a germ-cell, the origin 

 of whtch, according to Hofmeister's account in the above-named 

 places, actually takes place by free cell-formation. 



Fully as I trust in the acuteness and accuracy of Hofmeister's 

 obsenations, and desirable as the confirmation of his statements 

 would be to me, I have not yet succeeded in convincing myself 

 of their con-ectness ; I have seen a nucleus, and in later stages a 

 vacuole in that cell, but could never detect the formation of a 

 real daughter-cell in it ; on the contrary, the entire large cell in 

 every case appeared to become developed into the spore. If this 

 be really the case, it offers the iveightiest objection against too 

 close comparison both with the ovules of the Phanerogamia and 

 with the archegonium of the Crjptogamia, since a spore-forroa- 

 tiou of such a kind would rather point to a comparison with the 

 lower groups of the Cryptogamia, in which alone occurs spore- 



* Calcutta Journ. of Nat. Uist. vol. v. (1^14^. p. 241, 

 t rflanzeni»hysiol<»gic, iii. (1839), p. 354. 



