xiv SCIENCE PROGRESS. 



rence with it. Dr. Meyer, however, thinks the observations on which the view of excretion of 

 starch substance beyond the plastid is based are defective, and that a thin layer of the latter 

 always extends around the incipient and growing grain, although it needs very careful 

 staining by approved methods to make it visible. He further extends the amyloplastic powers 

 of the leucoplast and the chlorophyll grain to certain chromoplasts. 



Besides these researches based upon the normal grains as commonly seen, the book con- 

 tains some very valuable information upon the changes which the starch grain shows under 

 many varied conditions, the differences noticeable at different seasons, and the alterations in it 

 in the various organs of many different plants, taken from a very wide range in the vegetable 

 kingdom. Many ingenious experiments are narrated bearing on many of these points. They 

 are, however, of less general interest and indeed of less importance than the points of origin, 

 structure and fate which have already been alluded to. 



The work will have a great fascination for many workers in the field of vegetable physio- 

 logy. It is a pity that the language in which it is written will cause it to be less generally 

 useful to the English reader than its importance warrants. 



