GOG SUMMARY OF CURRENT RESEARCHES RELATINQ TO 



cbymatous tissue may possibly bo of an algoiil cbaractcr ; it is much 

 more difficult to account for tbe cellular appearance of the contents of 

 macrosporcs. 



Periderm of the Leguminosse.* — M. 11. Douliot states that in a branch 

 of Mi/ro:ci/Ion Pcrcira oi one year's growth a periderm formed exteriorly 

 of centripetal cork-layers may be seen, the cells of which are tabular, 

 and preserve their thin appearance ; there is also a centrifugal plielloderm 

 somewhat less abundant. The case of the exodermic (sub-epidermic) 

 periderm may be seen in a number of genera. In Hijmencea Courharil 

 the cork remains thin and the cells tabular, the tangential septa being 

 nearer one another than the radial divisions of the mother-cells of the 

 periderm. The plielloderm is composed of two or three layers of cells, 

 and the cork of about a dozen. There are two groups of Legnminosa) 

 in which the periderm is formed in the cortex ; and in certain species of 

 this natural order the periderm is pericyclic. A good example of this 

 may be seen in Soja Idspida. 



Anomalies in the Structure of the Roots of Licotyledons-f — Sig. 

 C. Avetta distinguishes between two types of anomalies in tlie roots of 

 Dicotyledons : — (1) Those produced by the generating zone due to an 

 inequality in the proportion and nature of the secondary tissues formed 

 by the cambial zone at various points in the circumference ; and (2) Those 

 produced by the pericycle, due to the formation of new collateral 

 bundles in the secondary parenchyma, resulting from the generating 

 activity of this pericycle. Under each type a number of special cases 

 are described. One of the varieties of the second type, occurring in the 

 Polygonaceae, affords the only example of supernumerary bundles formed 

 in a centripetal direction. 



Comparative Anatomy of Malvaceae, Bombacese, Tiliaceae, and Ster- 

 culiacese.^ — M. A. Dumont states that among the Malvaceae, the genus 

 Malva, and especially M. oxyacantlwides, may be taken as representing 

 the fundamental primitive type. The secondary liber is sharply divided 

 into layers ; the three cortical zones, the pith, the epidermis, and the 

 mesophyll of the leaves, contain numerous gummy elements. In this 

 family the essential characters undergo from one species to another 

 certain modifications and gi-adual attenuations, corresponding to the form 

 and disposition of the reproductive organs. The ditfercnt species of the 

 family thus form a descending series. 



In conclusion, the author states that Malvacese, Bombacese, Tiliaceae, 

 and Sterculiaceje so closely resemble one another in the structure of 

 their stems and their leaves, and in the organization of their flowers and 

 their fruits, that an anatomist would not hesitate to unite them in one 

 and the same natural family. By the help of anatomy, the tribes may 

 be divided into secondary groups, and these secondary groups ought to 

 be considered as groups containing a certain number of species in which 

 the characters have undergone modifications of about the same value 

 from that of the fundamental type. 



* Morot's Journ. Bot., ii. (1888) pp. 71-6 (7 figs.). 



t Ann. R. 1st. Bot. Koma, iii. (1887). See Morot's Journ. Bot., ii. (1888) Rev. 

 Bibl., p. 9. 



J Ann. Sci. Nat. (Bot.), vi. (1887) pp. 129-246 (4 pis.). 



