76 Scientific Intelligence. 



made use of what we may fairly call one of the-useless characters 

 in his classification, namely, the striations and stratifications which 

 belong to certain elements of these groups of plants. So far as 

 these markings are mechanical in their nature, they are obviously 

 to be classified among the useful modifications, but where they 

 are slight, they appear to fulfil no important function, and hence 

 can be used just as the stipules of Rubiacese are, for diagnostic 

 characters. The same may be said of the characters of the ele- 

 ments of the pith. Lastly it must not be forgotten that every 

 contribution to this subject adds to the records already at hand 

 for the identification by the microscope of species, genera, and 

 orders, of which only imperfect specimens are known. 



B. Researches on the origin and development of canals and 

 receptacles for secretions; by A. LeBlois. (Ann. Sci. Nat. ser. VII, 

 vi, p. 247. — This subject is allied to the last. In canals and 

 receptacles for secretion we have conspicuous organs which are 

 widely diffused through the orders of flowering plants, and in 

 some cases have distinctly biological offices of attraction, protec- 

 tion, and the like. But in some other familes, these organs are so 

 much reduced that they can hardly be believed to subserve any 

 important office, and in a few they exist as mere vestiges. Van- 

 Tieghem has been successful in utilfzing these organs for class- 

 ificatory purposes in the case of Myrtacese, where he has applied 

 what may be fairly called a quantitative method. Trecul and 

 Miiller have also devoted much attention to the examination 

 of this important subject, but even yet comparatively little 

 is known about the matter. This last contribution, by Le- 

 Blois, adds many interesting details of an apparently trust- 

 worthy character, and gives also some results of physiological 

 speculation. His conclusions may be given with little change in 

 form. The tissues under consideration, are living (in distinc- 

 tion from those which, like tracheae, have passed through their 

 development and have become non-living), and they are always 

 produced by division and separation, never by destruction and 

 absorption of cells. Further, they are secreting tissues. They 

 appear under two forms, the canal and the receptacle, in both 

 cases generally surrounded by a protective sheath. The two 

 forms are met with either isolated or conjoined. Proper recep- 

 tacles for secretions are never met with in roots, but they are 

 frequently observed in leaves. The secreting system is preco- 

 cious in development, either in the embryo, as in some cases, or 

 in parts arising later. g. l. g. 



2. The Botanical Works of the late George Engelmann. 

 Collected for Henry Shaw, Esq., an d edited by William Tre- 

 lease and Asa Gray. Cambridge, 1887. — This large quarto vol- 

 ume comprises the results of Dr. Engelmann's researches prosecuted 

 during the scanty leisure of a laborious profession. His earliest 

 paper relates to the morphology of plants, and brings out clearly 

 the main principles which underlie the structure of Phanerogams. 

 This was Dr. Engelmann's inaugural thesis and formed a fitting 



