8G SUMMARY OF CURRENT RESEARCHES RELATING TO 



of cellulose are not nearly so strongly develoi)e(l. The pollen-grains 

 are unicellular till shortly before pollination. As this time approaches 

 the starch-grains disappear. The single small cell which occurs in 

 Taxus is then formed by division, constituting the unicellular pro- 

 thallium. When the prothallium is multicellular its cells are 

 produced by successive divisions of the large cell behind those 

 previously in existence ; but this process is more readily seen in the 

 CycadesB than in the Coniferfe. The author traces a close analogy 

 between the formation of the prothallium of Gymnosperms and that of 

 the male prothallium of Vascular Cryptogams, especially of Isoetes. 



The pigments used by the author are methyl-green, anilin-red, 

 eosin, alum-carmine, and picric acid. 



Conduction of Pollen-tubes.* — Holzner ascribes to the outer 

 integument of the ovule in Hordemn and Bromus an important 

 function in assisting the pollen-tubes to reach the embryo-sac. The 

 cells of this integument are of the same nature and have the same 

 contents as those of the conducting tissue of the style, with which 

 they are in direct connection. 



Female Flowers of Coniferae.t — Professor Eichler's paper on 

 this subject has induced L. Celakovsky to reinvestigate it. After 

 reviewing the different theories and exjilanations enunciated since 

 Robert Brown's time, he dwells emphatically on the great importance 

 of the study of the annmorplioses (as he calls those monstrosities which 

 are the result of retrograde metamorphosis, in contradistinction to 

 mere pathological changes) and of the teaching they convey. He 

 comes to the conclusion that these are a much safer guide than the 

 microscopic study of the genesis of the organs, which has often 

 misled those who too implicitly relied on its teachings. Investigating 

 the anamorphoses of the Norway spruce, he finds the two lateral 

 carpellary leaves distinctly indicated, and more or less separated and 

 developed. In a more mature state an anterior and then a posterior 

 bract make their appearance ; these. Professor Eichler had taken for 

 a third and fourth lobe of his ligula (normally the posterior bract is 

 the third and the anterior the fourth in order). Celakovsky comes to 

 the conclusion that, at least in Abietincfe, Eichler's theory (that the 

 carpellary scale is a mere emergence or ligule of the bract) is quite 

 wrong, and that Mohl's view of 1871 that the carpellary scale of these 

 plants consists of the two connate lowest leaves of an axillary, other- 

 wise undeveloped, bud connate at their upper edge and producing the 

 ovules on their back, is amply vindicated by all known morphological 

 facts, and is antagonistic to none of them. 



He further concedes that the same explanation may possibly be 

 the true one for all conifers, and that all morphologists who have 

 treated this question thus far, have, whatever their views, assumed a 

 conformity in this respect in all the tribes of conifers, and a complete 

 homology of their female organs. But he thinks that this is not 



* SB. Versammlung cleutscher Naturforscher u. Aerzte in Eisenach, Sept. 19, 

 1882. See Bot. Centralbl., xii. (1882) p. 107. 



t Abh. K. Bohm. Gea. Wiss., xi. See Bot. Ztg., xl. (1882) p. 870. 



