88 THE TOXINS OF THE HIGHER PLANTS AND ANIMALS. 



It is the seed of croton tiglium that gives rise to crotin, a substance less 

 Crotin. poisonous than either ricin or abrin. It does not agglutinate, but hemo- 



lyses rabbits' red blood cells. Toward the red blood-cells of other 

 species of animals (e.g., bird), it is entirely inactive. The immunization of rabbits is 

 readily brought about by subcutaneous injections. Their serum neutralizes the hemo- 

 toxic action in vitro. 



The pollen toxin has been described by Dunbar as the etiologi- 

 Hay-fever. cal factor of hay-fever. In Germany the disease seems to 



come chiefly from pollen of the grasses and grains. (Rye 

 pollen being most active) ; whereas in America, apparently, the most impor- 

 tant pollen springs from members of the ambrosia (rag weed) and solidago 

 (golden rod). 



The toxin is isolated by mixing for ten hours the ground pollen with 5 per cent. NaCl 

 solution and 0.5 per cent, phenol at 37 C. Then, in the form of a proteid it is precipi- 

 tated by the addition of eight to ten volumes of 96 per cent, alcohol and the resultant 

 white precipitate dissolved in physiological salt solution. 



Susceptibility to the pollen toxin is limited only to certain individuals. 

 Some are influenced by the rye pollen only, others by the golden rod alone, 

 while a third class is affected by all. The cause for this peculiar idiosyn- 

 cracy is unknown. 



All those who suffer from hay-fever develop a marked conjunctivitis whenever even 

 the slightest amount of pollen proteid (i/iooo mg.) is dropped into the conjunctival sac. 

 In addition, all the symptoms of hay-fever or asthma may be incited. Similar effects 

 are in evidence when subcutaneous injections are resorted to. 



For purposes of immunization horses are most suitable, but only those 

 which after an injection of pollen extracts manifest a local and general reac- 

 tion. This is found in one-third of the cases. Their serum rendered 

 immune is capable of neutralizing all effects of the pollen toxin. 



As regards the standardization of this serum, it is effected by mixing the 

 dosis minima certe efficax of the toxin with various dilutions of the serum 

 and instilling the mixture into the conjunctival sac of individuals with a 

 tendency for hay-fever. That amount of the serum which suffices to neu- 

 tralize the toxic ravages is taken as the unit of measure. Sera of at least 

 thirty times the unit strength are employed. 



The immune serum is manufactured in fluid and powder form by Schim- 

 mel & Co. of Miltitz, near Leipzig, and is placed on the market under the 

 name of "Pollantin." Its use is mainly local, and that by spraying a 

 small quantity of the pollen powder upon the nasal mucosa several times 

 daily and by placing "several granules into the conjunctival sac with a 

 camel's-hair brush. The serum can also be employed as a prophylactic. 



If the eyes are especially reddened, it is best to deposit some fluid serum 

 into the conjunctival sacs every day. Prausnitz advises the injection of i 



