LYMPHATIC SYSTEM. 



[ 485 ] 



LYNGBYA. 



I 



nected with small openings left between the 

 epithelial cells, called stomata ; so that the 

 serous cavities and the lymphatic system are 

 directly continuous. The lymphatics in 

 their onward course unite, passing through 

 the lymphatic glands, forming longer ves- 

 sels, ultimately terminating by two trunks, 

 one of which is the longest and called the 

 thoracic duct, and which terminate in the 

 angle formed by the internal jugular and 

 subclavian veins on each side. 



The lymphatic or conglobate glands con- 

 sist of a capsule, composed of connective 

 tissue with scattered tine elastic fibres, and 

 in animals unstriated muscular fibres. The 

 substance of the glands consists of a cortical 

 and a medullary portion. 



The cortical portion, which in the larger 

 glands forms a layer about 1-0 to 1-4" in 

 thickness, exhibits a coarsely granular ap- 

 pearance, visible externally through the 

 capsule. This arises from the presence of a 

 large number of septa or trabeculje pro- 

 longed from the capsule into the substance 

 of the organ, and dividing it into alveoli ; 

 these are about 1-96 to 1-36" in diameter, 

 and of a rounded or polygonal form ; they 

 are more distinct in animals than in man. 

 The septa consist of connective tissue with a 

 few tine elastic fibres, and numerous delicate 

 spindle-shaped bodies, often anastomosing 

 at their ends. 



The contents of the alveoli are greyish 

 white, pulpy, traversed by capillary blood- 

 vessels, and by numerous delicate hbres, 

 with spindle-shaped and stellate cells re- 

 sembling those found in the septa, but form- 

 ing a lacunar or spongy adenoid tissue. 

 The soft substance consists of free nuclei 

 and rounded cells, resembling those foimd 

 in the chyle and lymph. 



In the medullary portion, the retiform 

 tissue is very fine, closely filled with lymph- 

 corpuscles, and connected with a plexus of 

 lymphatics, ending in the efferent vessels. 



The afferent vessels penetrate the capsule, 

 pass through the septa between the alveoli, 

 and open into their lacuuc-e, which are not 

 lined with epithelium. From these, the 

 lymphatics of the medullary plexus arise, 

 to terminate in the eiferent vessels. 



The course of the lymph is from the 

 afferent vessels into the capsular network, 

 thence into the cortical and the medullary 

 sinuses ; from these into the network of 

 lymphatics of the hilus, and finally into the 

 efferent lymphatic vessels. 



The injection of the lymphatics is a very 



difficult matter. Partial injections may be 

 obtained by injecting the prussian-blue 

 lictuid into an aperture made in the dif- 

 ferent tissues or organs. The structure of 

 the glands is made out, in ordinary sections 

 well washed to remove the lymph-corpus- 

 cles. See on these matters, Rutherford's 

 little ' Practical Histology.' 



The lymph, or liquid contained in the 

 ordinary lymphatics agrees essentially with 

 the chyle, except that the molecular base is 

 absent ; the white corpuscles forming the 

 characteristic microscopic elements. These 

 are described at p. 101. 



Lymphatics in Amphibia, — The structure 

 and arrangement of the larger lymphatics 

 differ in the Amphibia. They do not form 

 cyhndrical tubes, but lacunae, which occupy 

 the interspaces between the different organs, 

 the surface turned towards the interior of a 

 cavity being covered with a single layer of 

 tessellated epithehum. These cavities or 

 sacs communicate with each other by means 

 of microscopic openings. As there are no 

 contractile tissues in the walls of the sacs 

 special contractile organs acting rhythmi- 

 cally, or lymph-hearts, are superadded. A 

 very visible one in the frog is close to the 

 sacrum, and pnmps the lymph into the 

 sciatic vein ; another propels it into the 

 jugular. They are chietiy composed of 

 transversely striated short muscular laminae. 



BiBL, Kolliker, Mik. Anat. ii. ; Todd & 

 Bowman, Phi/s. An. ii. ; Lane, Todd's CycL; 

 Teichmann, D. Saugad., 1862 ; Briicke, Sitz. 

 Wien. Akacl. 1852-18/)5 ; His, Zeits. iviss. 

 Zool. xi., xii.,xiii. ; Recklinghausen, Stnclcer''s 

 Hist, i.; E. Klein, Lxjmph. Si/st., 1873; Sap- 

 liej,An.Si-Pht/s. d.vaiss. lymi?h., 1876; Frey, 

 Hist. 1876, and the lit. 

 _ LYNG'BYA, Ag.— A genus of Oscillato- 

 riacese (Confervoid Algas), related to Culo- 

 thrix and OsciUatoria, distinguished from 

 the former by its stratiffed habit, from the 

 latter by the long flexile but not oscillating 

 filaments. It contains both freshwater and 

 marine species. L. muralis (PI. 8. fig. 10) 

 grows in damp places and in water. The 

 specific characters are not satisfactory; but 

 we have found what we take to be L. 

 siagnina, Kiitz. Tab. Phyc. i. pi. 87. fig. 5, 

 and L. concinnata, KiiJ:z. I. e. pi. 89. fig. 5, 

 in fresh water. L. speciosa, Cannichaelii, 

 and ferruqinea, marine species, are figured 

 in Engl. Bot. Supp. Nos. 2926-27 a and h. 



These plants appear to break up into lenti- 

 cular gonidia ; but their reproduction, like 

 that of OsciUatoria, is very obscure. 



