June 4, 1909] 



SCIENCE 



907 



tion type might be called 0. Lamarckiana rubri- 

 nervis. 



On the Nature of the Fertile Spike in the Ophio- 

 glossacew: M. A. Chbysiieb, University of 

 Maine, Orono, Me. 



A study of the vascular system of the leaf in 

 the OphioglossaceaB supports the view that the 

 fertile spike is to be regarded as two fused pinnae, 

 viz., the two basal ones, which are comparable to 

 the fertile pinnse of Osnxunda Claytoniana and 

 Aneimia spp. It is found in Botryohium that the 

 vascular supply of the fertile spike is double; 

 that the two bundles arise_ from a curved leaf- 

 trace, at or near its extremities, and higher up 

 approximate but do not fuse. The vascular 

 bundles of the sterile pinnae arise in a manner 

 identical with that of the vascular bundles of the 

 fertile spike. The mode of origin of the bundles 

 of the fertile spike in each species of Botryohium 

 examined may be paralleled by that seen in vari- 

 ous genera of ferns, especially Osmunda. The 

 genus Ophioglossum may be derived from the 

 simpler species of Botryohium, while Belmintho- 

 stachys shows certain complications. These facts 

 point to the conclusion that the Ophioglossaceae 

 are to be regarded as a specialized family of ferns, 

 rather than as a primitive order of pteridophytes. 

 Origin of Heterospory in Marsilea: C. H. Shat- 

 TUCK, Clemson College, S. C. 

 It is possible by means oi a spray of cold water 

 to kill the megaspores, which occur only in the 

 oldest sporangia and then, putting the plant under 

 good conditions, to mature\ sporocarps without 

 megaspores. The greatest variation occurs when 

 the megaspores and oldest microspores are blasted. 

 Enlargement does not appear among the micro- 

 spores when less than half the spores abort, and 

 tne surviving spores are larger the greater the 

 amount of abortion. The mother cells may be 

 cheeked in their development till the tapetal 

 nuclei completely invest them. A perinium will 

 then form around the four nuclei, sometimes en- 

 closing them during the first and second mitoses. 

 In such cases the sporangium invariably contains 

 sixteen large bodies, each containing four nuclei. 

 At other times when growth is less checked, the 

 spores are more or less completely free and show 

 great variation in size and shape. 



The contest for supremacy among the young 

 megaspores is very evident, many of them assum- 

 ing considerable proportions, but one, centrally 

 located, invariably secures the ascendancy. Some- 

 times the contest is very close between two or 

 more members of the same tetrad. Very often the 



surviving member will carry attached to its papilla 

 the aborted members even to germination. 



The enlarged microspores vary in size from 

 eight to sixteen times that of the normal ones, 

 the nucleus shifting from a central (normal) to 

 an apical position as in the megaspores. As vacu- 

 olation is more extensive the shape of the nucleus 

 also varies from the normal spherical form to the 

 oval, and finally, in the largest to the meniscus 

 shape in the megaspore. 



In extreme cases of abortion in the microspo- 

 rangia only one spore survives which is about 

 sixteen times as large as the normal microspore. 

 The aborted tetrads remain as in the megaspo- 

 rangium, but better developed, thus showing a 

 sharper contest for supremacy. 



In plants kept from fruiting till September 1, 

 many microsporangia (by position) developed 

 megaspores and a few megasporangia developed 

 microspores. In such cases the megaspores were 

 intermediate in size and were also more nearly 

 the spherical shape of the microspores. A few 

 cases were noted in which the megaspores did 

 not develop a perinium but enlarged considerably 

 and became gorged with starch. Marsilea may be 

 made to repeat, under culture, all the phases in 

 the development of heterospory reported by Will- 

 iamson and Scott for both Calamostachys Ben- 

 neyana and G. Cosheana. 



Movements and Reactions of Fern Spermatoeoids : 

 W. D. HoYT, Johns Hopkins University, Balti- 

 more, Md. 



The movements of the spermatozoids of ferns 

 are complex and varied and depend on the condi- 

 tions in which they are placed. When the condi- 

 tions are unfavorable, they frequently reverse 

 their direction of rotation, and they swing their 

 anterior ends through a larger spiral and change 

 their direction of movement more often than they 

 do when in favorable conditions. The result of 

 this is favorable to the organism in that they 

 come in contact with a larger amount of the 

 medium and so stand a better chance of reaching 

 favorable conditions if these exist anywhere within 

 the medium. 



Difi'erent spermatozoids may react differently to 

 the same stimulus at the same time, and the same 

 spermatozoid may react differently to the same 

 stimulus at different times. In some cases these 

 differences in behavior can be ascribed to differ- 

 ences in physiological condition induced by differ- 

 ent past experiences. 



The cases where the movements have been suffi- 

 ciently slow for exact analysis indicate that ori- 



