PRESCRIPTION WRITING 81 



(1) Latin names of drugs ending in a form their genitive in ae. 

 The only exceptions are three: physostigma takes the genitive in tis, 

 physostigmatis; folia (leaves), pi. genitive, foliorum; theobroma, genitive- 

 theobromatis. In most instances the genitive of Latin nouns ending in a, 

 can be made in practice by dropping the nominative ending (a) and add- 

 ing 8B in its place, viz.: Tinctur-a (a tincture), genitive tinctur-ae (of a 

 tincture). 



(2) All pharmacopeial nouns ending in us, um (os and on), form 

 their genitive in i. This genitive case can be formed in practice by drop- 

 ping the nominative ending (us or um) and adding i in its place, viz.: 

 bol-us, a ball; genitive bol-i, of a ball. Extract-um, an extract; genitive 

 extract-i, of an extract. 



The nouns ending in os and on are very few. Exceptions: rhus, 

 genitive rhoisj flos, genitive floris. Fructus, quercus and spiritus do not 

 change in the genitive, as it is the same as the nominative case. 



(8) All other Latin names of drugs, of whatever termination 

 (except those ending as described under rules 1 and 2) have their geni- 

 tive in « and is. 



The genitive case can be formed in practice, in some instances, by 

 adding is to the nominative, as, for example ; chloral, genitive chloral-is ; 

 ether, genitive, ether-is. To many nouns ending in the nominative in as 

 or is, we not only add is to the nominative, but also change the latter 

 letter of the nominative case. For instance, to sulphas (sulphate) not 

 only do we add is, sulphas-is, but we change the latter letter, s, of sul- 

 phas into a f so that the proper genitive of sulphas is sulphat-is. 



The same remark applies to all the other Latin names of salts, as 

 sulphis, genitive sulphit-is; nitras, genitive nitrat-is; hydrochloras, geni- 

 tive hydrochlorat-is ; citras, genitive citrat-is; phosphas, genitive 

 phosphat-is ; acetas, genitive acetat-is. Cortex is not cortex-is in the geni- 

 tive, but corticis. Mas, genitive not mas-is, but maris. Adeps, genitive 

 not adeps-is, but.adipis. Mucilago, pepo and pulvis lengthen and change 

 in the genitive to mucilagin-is, pepon-is and pulver-is. Aloe, genitive not 

 aloeis, but aloes, adding s and not is. 



(4) Some Latin names of drugs do not change their ending in the 

 genitive because indeclinable and not Latinized, or else they belong to the 

 fourth declension, where the genitive case is the same as the nominative. 

 Examples: spiritus, quercus and fructus, already mentioned as excep- 

 tions to rule 2; Cannabis, digitalis, sinapis and hydrastis. The genitive 

 of these nouns is the same as the nominative. 



The following are indeclinable: amyl, buchu, catechu, coca, curare, 

 jaborandi, kino, cusso, gummi, etc. 



If the Latin names for quantities and amounts thereof are written out 

 in full (instead of using signs for quantities, and numbers for the 

 amounts), the quantities and amounts in Latin must be put into the ac- 

 cusative case, as they are the objects of the verb, recipe. 



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