108 VIRCIIOW'S JUICE-CONVEYING TUBES. 



centre of each space. From each a delicate fibre 

 extends, which intertwines with the fibres from adja- 

 cent masses of bioplasm. The bioplasm increases at 

 the circumference of each area, while the previously 

 formed tissue remains in the central part. Thus it 

 happens, when the tissue has grown to a certain ex- 

 tent, more or less circular spaces, occupied by a very 

 delicate fibrous tissue, are seen free from any bioplasm 

 whatever, while the latter exists only at the circum- 

 ference. These spaces increase in diameter as the 

 tissue advances in development. In this way growth 

 takes place equably in all parts of the tissue. 



The above appearances in the structure of the 

 tissue may be well seen under a low power in suffi- 

 ciently thin specimens prepared as I have described. 

 When examined under a magnifying power of 700 

 diameters, each elementary part is observed to con- 

 sist, 1, of the oval mass of bioplasm prolonged in 

 either direction for a short distance, and exhibiting 

 oil- globules in consequence of change having taken 

 place after death ; and, 2, of the delicate fibrous 

 tissue externally, which may be torn and frayed out 

 without difficulty. 



151. Virchow's Juice-conveying tubes. The ex- 

 tensions of the bioplasm into the fibrous tissue have 

 been mistaken for tubes, and it has been stated by 

 Virchow that these tubes anastomose throughout 

 the tissue, and constitute a system of channels for 

 the conveyance of the nutrient juices. But it 

 need scarcely be remarked, first, that the sup- 

 posed channels do not in all cases anastomose; 

 secondly, that they contain bioplasm and imperfectly 

 developed formed material, not fluid, as has been sup- 

 posed ; and, thirdly, that nutrition is more perfectly 

 carried on by the tissue itself being permeated every- 

 where by the fluid flowing to and from the bioplasm, 

 than it would be by any system of nutrient tubes like 

 that imagined to exist. 



