September 4, 1903.] 



SCIENCE. 



309 



cells or spongy tissue about tlie young game- 

 tophyte both in Thuja and in Pinus. He 

 considered that it was the presence of this 

 tissue whieli led Ilofmeister to conclude that 

 a transitory endosperm was formed in these 

 plants. So far as one is able to learn from 

 the literature, these early observations and 

 conclusions of Strasburger's have remained 

 unquestioned except by a few recent writers. 



In describing the development of the ovule 

 in Stangeria, Lang* (June, 1900) makes no 

 mention of a spongy tissue, but says : 

 ■■ Around the megaspore a layer of cells was 

 jiresent which is clearly to be traced to the 

 sporogenous group. The thick zone of sporo- 

 genous tissue present in earlier stages has, 

 however, become reduced to a single layer. 

 The cells of this persistent layer (Fig. 16) 

 are very large, and stand with the longer axis 

 at right angles to tlie surface of the mega- 

 spore. How long this layer of cells, which at 

 this stage shows no signs of crushing or dis- 

 integration, persists, can not at present be 

 determined; in the fertilized seeds all trace 

 of it was gone. In the light of the present 

 facts it would appear to be a probable con- 

 clusion that, while the majority of the sporo- 

 genous cells surrounding the embrj'o-sac sim- 

 ply become disintegrated and absorbed, the 

 outermost form a more definite tapetal layer. 

 This tapetum, while persisting longer than 

 the more internal cells, iiltimately disappears." 

 The figure 10 to which Lang refers shows the 

 persistence of this layer after the prothallium 

 has become a multicellular body. 



The manuscript of a paper by the writeif 

 dealing with the development of the pollen 

 tube in the pines had been in the hands of the 

 pi'.blishers some weeks before Lang's paper 

 appeared in America. It was not my pur- 

 pose to give a detailed description of the de- 

 velopment of the prothallium and related 



• Lang, 'Studies in tlie Development and Mor- 

 phologj- of Cyeadean Sporangia.' 11.. ' The Ovule 

 of Slangrria puradoxa.' Aun. Bot., 14: 281-300. 

 1000. 



t Ferguson, ' The Development of the Pollcn- 

 Tulio and the Division of the Generative Nucleus 

 in Certain Species of Pines.' Ann. Bot., 15: 193- 

 22.3. 1901. 



phenomena in that paper, inasmuch as this 

 was to form the basis of a later paper now 

 ready for publication; but incidentally the 

 following statement was made : " The prothal- 

 lium now consists of a uniform layer of 

 protoplasm in which numerous free nuclei are 

 embedded, no cell-walls as yet having been 

 laid down. Immediately surrounding the 

 endosperm, there is a definite band or hollow 

 sphere of cells which is limited on its outer 

 surface by a thin stratum of the disintegra- 

 ting nucellus. These two layers constitute the 

 so-called spongy tissue. The inner portion 

 of this tissue, i. e., the prominent band in 

 immediate contact with the prothallium, must 

 be intimately connected with the nutrition of 

 the young endosperm. The true structure 

 and function of this layer seem to have es- 

 caped the notice of previous writers. Its 

 cells contain large nuclei, and are abundantly 

 supplied with protoplasm. The karyokinetic 

 figures so frequently observed in these cells 

 show that this tissue increases in size by the 

 growth and division of its cells as do the other 

 portions of the ovule. As it enlarges, the 

 cells of the nucellus in contact with its outer 

 surface become disorganized and are absorbed 

 (Fig. 3)." The figure referred to shows the 

 prothallium and the disintegrating nucellar 

 tissue separated by a definite zone of tissue 

 two layers of cells in thickness. The cells of 

 this band are conspicuous for their size and 

 three of them show mitotic figures represent- 

 ing diiferent stages of division. In Fig. 4 

 of the same paper this tissue is shown to be 

 still present, but in a state of disorganization, 

 at the time when the iirothallium has become 

 a solid multicellular body, and shortly before 

 the division of the central cell. 



Coker* finds that in Podocarpiis " the 

 niacrospore arises deep in the nucellus and 

 is not surrounded by spongy tissue such as is 

 found in the Abieteff, Cupresseae, and Tax- 

 odiese, and which has so often been errone- 

 ouslj' described as of sporogenous character." 

 To this statement he adds the remark : " Miss 

 Ferguson's suggestion that the spongy tissue 



* Coker, ' Notes on the Gametophj-tes and Em- 

 bryo of I'odocarpus.' Bot. tjiiz., 33: 89-107. 

 1902. 



