554 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Antherozoids of Hepaticse and Mosses.* — In all the Hepaticse ex- 

 amined, belonging to very different types of structure — Pellia, Anthoceros, 

 FruUania, Marchantia, &c. — M. L. Guignard finds the mode of develop- 

 ment of the antherozoids to agree in all important points. Pellia 

 epipliylla may be taken as a type. 



The mother-cells of the antherozoids have a discoid form, one side 

 being flat and the other slightly convex ; they remain attached in pairs 

 by their flat faces until the maturity of the antherozoids, which are 

 formed singly in each of them. In the formation of the antherozoid the 

 nucleus of the mother-cell, at first central, moves to one side, and is 

 covered only by a very thin layer of protoplasm. It now elongates 

 greatly, and curves in a spiral manner; its anterior extremity, always 

 very thin, is in close juxtaposition to the thick posterior extremity; 

 finally the spiral attains three or four turns. The thin layer of 

 protoplasm which covers the outer surface of the nucleus becomes a 

 hyaline band which is continued as far as the opposite side, surrounding 

 the granular protoplasm. From it are formed the two cilia which 

 proceed from the anterior end of the antherozoid, and rapidly attain 

 their full length, which is equivalent to that of the spiral. The granular 

 protoplasm comprised in the spiral is gradually absorbed as the anthero- 

 zoid developes ; a very few traces only remain at the period of maturity. 

 The differences observed in other Hepaticae concern only the form and 

 size of the mother-cells, and the length of the cilia compared to that of 

 the spiral. 



The processes of development in the Musci are completely analogous 

 to those in the Hepaticse. In Sphagnum the body of the mature anthero- 

 zoid consists of only two turns of the spiral, of which the first is much 

 the larger, and, when escaping from the mother-cell, carries with it a 

 residue of protoplasm in the form of a vesicle inclosing some granula- 

 tions and a small quantity of starch. The two cilia, inserted at the 

 anterior extremity, which has somewhat the appearance of a button^ are 

 always rather longer than the body of the antherozoid. 



The mode of formation of the antherozoids of the Muscinese agrees 

 therefore, in all essential respects, with that of the Charace£e.| It is 

 the nucleus only which is transformed directly into the body of the 

 antherozoid ; the cilia being formed, at an early period, from a hyaline 

 layer of protoplasm outside the nucleus. The spiral body is homo- 

 geneous and chromatic, except in the posterior portion, where it is 

 somewhat less receptive to nuclear reagents. It is covered by a very 

 delicate hyaline envelope. 



Geotropism of the Rhizoids of Marchantia and Lunularia.J — 



From a careful series of observations on the development of the rhizoids 

 proceeding from the bulbils of Marchantia and Lunularia, Herr H. 

 Haberlandt states that growth in length takes place exclusively in the 

 cap-shaped apical portion of the rhizoid, where it is manifested with 

 extraordinary energy. The geotropic curvature is not exhibited, as has 

 been stated, in a zone of the rhizoid below this growing portion, but in 

 the growing portion itself. Under the influence of geotropism the 

 rhizoids never assume a vertical direction, but make an angle of from 



* Comptes Kendus, cviii. (1S89) pp. 463-4, and Rev. Gen. de Bot. (Bonnier), i. 

 (1S89) pp. 63-70 (1 pi.). t Cf. this Journal, ante, p. 417. 



I Oesterr. Bot. Zeitsclir., xxxix. (1889) pp. 93-8. 



