244 EXTRACTS AND ABSTRACTS FROM FOREIGN JOURNALS. 



The gum of the latex is, like that of the sap, similar to the gum of 

 starch. The sugar of the latex is always grape-sugar. 



4. New observations on the vessels of the latex and their kinds. In 

 those plants in which the acid of the latex (which juice always contains 

 an acid) is the gallic, as in the Musa paradisiaca ; the distribution of the 

 laticiferous vessels can readily be distinguished without any other pre- 

 paration, by placing a portion of a living leaf into a solution of a salt 

 of iron, which blackens the network of vessels, when it has penetrated 

 the tissues as far as the latex. 



5. Observations on the evolution of the laticiferous vessels, in the 

 cortical layers of trees. Some trees acquire several layers in a sum- 

 mer ; others require several years for the formation of one, which gra- 

 dually increases in thickness, and others form an annual layer. 



There is a great difference between the mode of formation of the 

 woody and cortical layers. 



6. Observations on the distribution of the latex in the contracted 

 vessels, and the cellular parenchyma of the medulla, of the epidermis, of 

 the hairs, &c. 



Donne on the Origin of the Blood- globules, their Mode of Formation, 

 and their Destination. In blood there are three kinds of particles : 

 1st. The red or blood-globules properly so called. 2nd. The white 

 globules, which have not been well known until lately. 3rd. The chyle 

 corpuscles. 



The red globules are flat in every kind of blood ; they are circular in 

 that of mammifers ; and elliptic in that of birds, fish, and reptiles. The 

 elliptic globules alone present a solid substance in their interior : the 

 existence of a central nucleus cannot be demonstrated in the circular 

 globules. 



Contact with water changes all the blood-globules into small spheres, 

 and it is to this circumstance, unknown to ancient observers, that we 

 must attribute the opinion of some of them respecting the spherical 

 form of the blood-globules of mammifers, as well as the spherical shape 

 which they supposed was present in the blood- globules of birds at the 

 time of their formation in the embryo : this shape is only secondary, 

 and is caused by the water which is made use of to dilute the blood, or 

 to prepare the embryo of the egg. 



The proper blood-globules of mammifers, or the circular globules, 

 are entirely soluble in acetic acid ; but the proper blood- globules of 

 birds, fish, and reptiles are only partly dissolved by it ; the internal 

 substance or nucleus resists the action of this agent. All blood-globules, 

 whatever may be their shape, or the class to which they belong, are 

 soluble in ammonia, and insoluble in nitric acid. 



The proper blood-globules, or the red globules, appear to be formed 

 of a flattened vesicle, containing a solid substance or nucleus in the 

 elliptic globules, and a fluid in the circular ones. 



The anomaly which has been remarked in the blood- globules of 

 CamelidcBy has reference only to their shape, and not to their intimate 

 structure, which is exactly similar to that of the blood-globules of other 

 mammifers. The white globules are colourless, spherical, with slightly 



