(j8C SUMMARY OF CURRENT RESEARCHES RELATING TO 



Arginin.* — This proteid, to which the formula C ET u N 4 O., is given 

 is found by M. U. Suzuki to be a constant ingredient of the seeds of 

 Ooniferse (Pinus Thunbergii, Cryptomeria japonica, Gingho biloha), and 

 to be peculiar to that family. It occurs also in the etiolated seedlings. 

 It appears to be formed both by the decomposition of albumen and also 

 synthetically out of ammonium salts. In other families of plants it is 

 replaced by asparagin. It appears to be used by the plant directly in 

 the regeneration of proteinaceous substances. 



Albumen-Crystalloids in Lathraea.j — Herr E. Heinrichcr finds the 

 proteid-crystals of Lathrsea — chiefly L. squamaria — not only in the 

 nuclei, but also in the cytoplasm and the leucoplasts. Those which 

 occur in the nucleus are found in all the vegetative organs of the plant; 

 but are wanting in the primitive mcristcm of the growing point. They 

 are to be found in seedlings six weeks old. The crystals which arc 

 distributed through the cytoplasm are exceedingly minute, and occur 

 also in all the vegetative organs; both kinds reaching a large size iii 

 the haustoria. The author claims to have definitely demonstrated that 

 these crystals are not artefacts, but are constituents of the living cell. 



(3) Structure of Tissues. 



Central Cylinder of Angiosperms.i — According to Dr. E. C. Jeffrey, 

 Van Tieghem's three types of vascular cylinder in the stem of Angio- 

 sperms, polystelic, astelic, and medullated monostelic, are but modifi- 

 cations of a single type, the siphonostelic, characteristic of Angiosperms, 

 Gymnosperms, and Filicales, as contrasted with Lycopodiales and 

 Equisetales. In this type the central cylinder is primitively a fibro- 

 vascular tube with foliar lacunae opposite the points of exit of the leaf- 

 traces. In the so-called polystelic modification, the central cylinder 

 has internal as well as external phloem, and may be described as 

 •" amphiphloic." In the so-called astelic type of axis, the internal 

 phloem is wanting, and the central cylinder may be termed " ecto- 

 phloic." The medullated monostelic type of Van Ticghem is derived 

 from the last-named by the suppression of the endoderm. 



Sieve-Tissue.§ — M. E. Perrot publishes a treatise on this subject, 

 including the elements which accompany the sieve-tubes in the phloem 

 of vascular plants. The wall of the meristematic cell which is destined 

 to become differentiated into a sieve-cell is at first uniformly thin and 

 composed of pectose-cellulose ; it early undergoes a notable thickening, 

 due entirely to the increase of the cellulose; this thickening coinciding 

 with the perforation of the transverse walls previously thickened in a 

 reticulate manner. These peculiarities of structure characterise sieve- 

 tubes in their state of greatest activity. In the leaf-veins the vessels 

 are accompanied by sieve-tubes right up to their extremities. 



In the sieve-tubes and the adjoining cells, sometimes also in the 

 laticifers, is a principle endowed, like diastase, with the power of de- 



* Bull. Coll. Agiic. Tokvo, iv. (1900) pp. 1-23, 25-07 (6 pis.), gee Bot. Cen- 

 tralbl., lxxxiii. (1900) pp. 354. 350. 



t Pringsheim's Jahrb. f. wiss. Bot., xxxv. (1900) pp. 28-47. 



+ Trans. Canadian Inst., vi. (1899) pp. 599-634 (5 pis.). 



§ Le tissu crible, Paris, 1S99 (122 figs). See Bull. Soc. Bot. France, xlvi. (1900) 

 p. 439. 



