16 a Mis. 53. 



formed and combined. To obtain a knowledge of the plan and pro- 

 cess of organization, we must begin with the most simple combina- 

 tions, precisely as we would do in the study of mathematical analyses, 

 in which the student commences with the least complicated formula, 

 and gradually proceeds to those of a more involved character. It is 

 for this reason that the study of the algae, or seaweeds, is of special 

 interest to the physiologist. The framework of every vegetable is 

 built up of cells or little membranous sacks. All vegetable structures, 

 W'hether wood, bark, or leaves, are formed of aggregations of these 

 cells, differently moulded and united. As we pass along the 

 series of organized forms, we may descend from those of a higher to 

 those of a lower complexity, until, in the class of algae, we arrive at 

 plants of which the whole body is composed of a few cells strung 

 together ; and finally at others, the simplest of organized bodies, whose 

 entire framework is a single cell. Now, it is only by a critical study 

 of these rudimentary forms, and by tracing them into their complex 

 combinations, that man can ever hope to arrive at a knowledge of the 

 laws of organization. We might speak of the importance of a know- 

 ledge of the algte in their application to agriculture and the chemical 

 arts. But what we have here stated will be a sufficient reason for 

 tlieir study, independent of all minor considerations. 



The next memoir consists of an account of a series of researches in 

 the comparative anatomy of the frog, by Dr. Jeffries Wyman, of Cam- 

 bridge, Massachusetts. 



The whole animal kingdom may in one sense be considered as the 

 different development of four separate plans of organization, giving 

 rise to four different classes of animals, viz : the Radiata, the Articulata, 

 Mollusca, and Vertebrata. Whatever discovery is made with regard 

 to the organization of any of the species belonging to any one of these 

 classes, tends to throw light on the organization of the whole class, 

 and it is only by the careful study of all the different animals of a 

 class, and a comparison of their analogous parts, that we can arrive at 

 a knowledge of the general laws which pervade the development of 

 the whole. Thus the study of human anatomy is the basis of the 

 investigation of the anatomy of all animals with a back-bone; and 

 conversely, the anatomy of any animal of this class tends to throw 

 light on that of man. 



Dr. Wyman's paper gives an account of a series of elaborate inves- 

 tigations of the nervous system of a very common, but, in a physio- 

 logical point of view, highly interesting animal. 



The following are the several points of the memoir: 



1. An anatomical description of the more important part of the ner- 

 vous system. 



2. Comparisons between them and the corresponding organs or 

 other animals, both higher and lower in the scale. 



3. The metamorphoses which they undergo, especially the spinal 

 chord and some of the cranial nerves, showina; the existence of a more 

 complete analogy between the nnmature condition of Batrachian rep- 

 tiles and the class of fishes, than has hitherto been noticed. 



4. An application of the facts observed in connexion with the cranial 

 nerves to the philosophical anatomy of the nervous system, showing 



