ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 537 



from the Protophyta. The Gymnosperms appear in the Carboniferous 

 period, but only to a very subordinate extent. All the groups of 

 Cryptogams had by that time been differentiated. The highest type 

 of Cryptogams was defeated in the struggle for existence by the 

 Gymnosperms and Angiosperms. 



Organic Unicellular Bodies in Coal.* — Further investigation of 

 the peculiar organic bodies found in coal by P. F. Eeinsch confirms 

 him in the view that they are of two kinds totally different from one 

 another. The smaller or Triletes-tovia. bears a remarkable resemblance 

 to the spores of Sphagnum, and may probably be bodies of this de- 

 scription. They occur in such enormous quantities in some Eussian 

 coal as to constitute from 80 to 90 per cent, of its mass. A cubic 

 centimetre may contain 5,827,000 of them, having an average diameter 

 of • 033 mm. The larger of these bodies are of a totally different 

 nature, and are probably independent organisms forming a stage of 

 development of some very simple plant-form. 



Cryptogamia Vascularia. 



Fibrovascular Bundles of Vascular Cryptogams, f — According 

 to H. Potonie the terms xylem and phloem have neither a physiological 

 nor a definite morphological meaning as applied to the vascular 

 bundles of cryptogams. By phloem nothing further is to be under- 

 stood than the part of the bundle which contains sieve-elements, and 

 by xylem that part which contains the tracheids ; without associating 

 with these ideas any definite limitation of these portions of tissue. 



As respects the fi.brovascular bundles themselves, everything must 

 be regarded as belonging to the bundle which stands in an unquestion- 

 able physiological relationship to it as an anatomico-physiological 

 unit of a high order. The mechanical adjuncts, therefore, which 

 often inclose or accompany the bundle must be regarded as belonging 

 to it. 



The stereome which commonly surrounds the bundle in the form 

 of strings, is sometimes found within the mestome, as in Adiantum 

 trapeziforma. The tracheome is, according to the most recent obser- 

 vations, not the tracheal but the hydral system of the bundle, and 

 may therefore be called the " hydrome." The function of the " amy- 

 lome," or parenchymatous elements which usually contain starch, is 

 to convey the carbohydrates. The starch-cells which often occur 

 among the hydroids, but which are apparently not connected with one 

 another by equivalent elements, form a continuous system. The 

 hydrome and a portion of the amylome constitute together a system 

 of a higher order, the " hadrome." The osmotic force of the amylome 

 either exhausts the hydroids of water or fills them with it. This 

 physiological relationship explains the remarkable facts that where a 

 number of hydroids lie close together the hydrome is regularly per- 

 meated by threads of starch, and that all vascular cryptogams possess 



* Flora, Ixvi. (1883) pp. 187-9. Cf. this Journal, ante, p. 409. 

 t Jahrb. K. Bot. Gartens Berlin, li. (1883) pp. 233-78 (1 pi). See Bot. 

 Centralbl., xiv. (1883) p. 100. 



